How does one cope with despair using Buddhist practises?

Your melancholia is due to your desire. It is evident in your writing that you have desire: you want to escape from pain. You desire different moods and experiences.

For example, today, just after the workout and a good meal, I felt severe, yet inexplicable, mental suffering

That is the desire I am talking about. You still believe that exercise and food, sensual pleasures, will eliminate dukkha. You are trying to think your way out of depression by searching for that which causes it. Your depression spawns from your thinking: trying to figure out why you are depressed. Since you can't figure out why, then you endlessly ruminate.

It's a catch-22, and it gets worse the more you engage in it.That is kamma.

You need to find ways to uplift the mind, such as chanting or recollecting on the precepts, the triple gems, or recollecting on nibbana.

Good exercise and healthy diet daily. When the body is healthy, it's a lot easier to tame the mind. Follow the Mayo clinic guideline for recommended daily amount of exercise.

Samana Johan gave a good answer,do that.

Furthermore get some admirable friends, do not associate with shitty people. Good company in definitive sense is all of the holy life. No friendship with fools.

I will add that Buddha praised giving gifts, he also told householders to not be content having provided gifts to the Sangha but to also attain 'seclusion'.

Lord, when a disciple of the noble ones enters & remains in seclusion & rapture, there are five possibilities that do not exist at that time: The pain & distress dependent on sensuality do not exist at that time. The pleasure & joy dependent on sensuality do not exist at that time. The pain & distress dependent on what is unskillful do not exist at that time. The pleasure & joy dependent on what is unskillful do not exist at that time. The pain & distress dependent on what is skillful do not exist at that time. When a disciple of the noble ones enters & remains in seclusion & rapture, these five possibilities do not exist at that time."

It does not need to be a 'deep meditative state'. Ie if one thinks about virtue, the buddha, one's good deeds it can be accompanied by gladness and be quite pleasant.

These states at that time are secluded from the five things that don't exist at that time.

You could try finding themes of ideas to entertain which work to seclude by directing elsewhere.

"Whatever a monk keeps pursuing with his thinking & pondering, that becomes the inclination of his awareness. If a monk keeps pursuing thinking imbued with sensuality, abandoning thinking imbued with renunciation, his mind is bent by that thinking imbued with sensuality. If a monk keeps pursuing thinking imbued with ill will, abandoning thinking imbued with non-ill will, his mind is bent by that thinking imbued with ill will. If a monk keeps pursuing thinking imbued with harmfulness, abandoning thinking imbued with harmlessness, his mind is bent by that thinking imbued with harmfulness.

This is how it comes about.

When one trains ie mindfulness of breathing, it's also called 'perception of in and out breaths'.

One can basicly sit perceiving the in and out breaths. One can contemplate their cessation and impermanence, at that time one's theme is also impermanence and one trains perception of impermanence. One should be mindful of the arising, the persisting and the passing away in regards to feelings and perceptions.

If mind is not easily calmed by the perception of in ans out breathing, one should direct the mind to a different theme. There are too many to list, i have a list tho; https://docs.google.com/document/d/1kZxstsAvjhj9Svc47RUKRIyKQMuHMD4adIvr_7pp2uI/edit?usp=drivesdk

Sluggish/Tired Mind

"At such times, monks, as the mind is sluggish, that is the wrong time to cultivate the enlightenment-factor[1] of tranquillity, the enlightenment-factor of concentration, the enlightenment-factor of equanimity. What is the reason? A sluggish mind is hard to arouse by these factors. "But, monks, when the mind is sluggish, that is the right time to cultivate the enlightenment-factor of investigation-of-states, the enlightenment-factor of energy, the enlightenment-factor of rapture.[2] What is the reason? A sluggish mind is easy to arouse by these factors.

Aroused/Active/Agitated Mind

"Monks, when the mind is agitated,[3] that is the wrong time to cultivate the enlightenment-factors of investigation-of-states, of energy, of rapture. Why? An agitated mind is hard to calm through these factors. "When the mind is agitated, that is the right time to cultivate the enlightenment-factors of tranquillity, concentration, equanimity. Why? Because an agitated mind is easy to calm[4] through these factors.

Buddha definitely taught directing the mind;

“There is the case of a monk who remains focused on the body in & of itself—ardent, alert, & mindful—subduing greed & distress with reference to the world. As he remains thus focused on the body in & of itself, a fever based on the body arises within his body, or there is sluggishness in his awareness, or his mind becomes scattered externally. He should then direct his mind to any inspiring theme. As his mind is directed to any inspiring theme, delight arises within him. In one who feels delight, rapture arises.

In one whose mind is enraptured, the body grows calm. His body calm, he feels pleasure. As he feels pleasure, his mind grows concentrated.

He reflects, ‘I have attained the aim to which my mind was directed. Let me withdraw [my mind from the inspiring theme].’ He withdraws & engages neither in directed thought nor in evaluation. He discerns, ‘I am not thinking or evaluating. I am inwardly mindful & at ease.’

“This, Ananda, is development based on directing.

And what is development based on not directing? A monk, when not directing his mind to external things, discerns, ‘My mind is not directed to external things. It is unconstricted [asankhitta] front & back—released & undirected. And then, I remain focused on the body in & of itself. I am ardent, alert, mindful, & at ease.’

“When not directing his mind to external things, he discerns, ‘My mind is not directed to external things. It is unconstricted front & back—released & undirected. And then, I remain focused on feelings… mind… mental qualities in & of themselves. I am ardent, alert, mindful, & at ease.’

“This, Ananda, is development based on not directing.

If want to read more details on meditation and overcoming hindrances; https://docs.google.com/document/d/1hRy-g6o8yKsDQnR6_sbBbY5ZVpDbQ5-_LURXqwxS7YU/edit?usp=drivesdk

You should separate your thoughts categorically as to whether they are associated with desire,anger or delusion; or not associated.

Then you start actively calming the bad ones as instructed here; https://www.accesstoinsight.org/tipitaka/mn/mn.020.than.html

https://www.accesstoinsight.org/tipitaka/mn/mn.020.than.html

May your body chemistry respond to your aspirations, friend.

Medicine Buddha study suggests these steps:

Know the sickness.

Abandon the cause of the sickness.

Aspire the cure.

Rely upon practices that release / transform the power of the sickness.

For me the practice of Tonglen is reliable. Recognize that many others struggle with the same sickness. Sincerely Offer in your heart, to bear it for them since you are so familiar with it already. Offer them a break. Evoke an experience of relief you have accessed in your life. Send out that experience as a gift to the others suffering as you are. In this practice you may find your own feeling of dark isolation, even to self pity, is lightened and released, even if only a little at a time.

I use this lately for despair, sorrow, guilt, rage and fear triggered by world conditions and human failure. I feel personal failure, guilt of not doing enough, grand delusions my lifelong service to prevent environmental trends we see today should have Worked. Tonglen helps me as I imagine others I admire who have served so nobly to released from this kind of despair and pain.I need to do this often!

I wish you freedom in your life, moment to moment, in your way forward. you are well equipped. You can abandon the cause of your sickness, lifted away from it as you aspire to health and joyful mind for yourself and others like you.

Thank you for sharing of yourself here.

I don’t think I have experienced anything comparable to your situation so my suggestion may or may not work for you. Personally, I find mindfulness meditation useful. It would fall somewhere between open monitoring and focused attention. Specifically, the attention is on the state of the mind. To do so we want to do a comparison of the mind’s state or well-being at various points throughout the day.

This mindfulness technique requires a consistent effort throughout your waking hours, it involves taking a pause to check and reflect at intervals, like once or twice each hour. Ask yourself mentally where is the mind or in what state is your mind. Take note of your mind’s state at intervals throughout the day. The intervals can be longer or shorter, just don’t forget and pick up again if you fail to remember. The trick is to let this pause, check and reflect be as natural as possible so that it becomes habitual.

Try to compare the mind’s state versus the previous checks, is it better or worse? If it is worse, try to figure out if there is anything that causes the deterioration. If it is better, try to understand the cause as well. Try to avoid those causes that result in a degradation of the mind’s well-being and encourage those causes that improve the mind’s well-being. If there’s no change, check again if you had ignored any changes (in terms of feeling, emotions, mental clarity, anxiety, stress and so on). If not, just maintain the practice.

The aim is not to allow your mind to be caught unconsciously or unintentionally at a cliff’s edge but to have enough early warning if it is heading in the wrong direction. It takes far less effort to steer your mind away from the edge than to slow down its momentum when it is falling. And if in spite of all these, you still suffered from an episode, try to pause (hopefully, this is habitual by now that you have enough presence of mind to temporarily halt the onslaught) and rewind to maybe 10 or 15 min ago and reflect on what was the state of your mind then. Was it OK then. If it was, ask yourself if there was any trigger. Sometimes, the trigger is not obvious but the mind is already primed to fall into depression over a period of hours and maybe even days or longer. It's like being on the edge of a precipice….just the slightest nudge and off it goes. In that case, you need to rewind to even further back like hours or even days or longer. The idea is that it is easy to detect an avalanche but hard to detect the conditions that gradually build up an avalanche. And it is this gradual build-up that we usually fail to catch but that turns into an avalanche once it reaches a tipping point.

Lastly, I think it is far easier to check and catch the mind’s state i.e. whether it is experiencing a low or high tide, if we are at normal level most of the time. In your case, I assume it maybe already at a low level (i.e. low energy, melancholic, anxious or unease) so I am not sure if this technique will work out for you. May this be useful, with Metta!

Don't allow your mind to stop your metta practice. Mind should be controlled. When I feel bad I do metta. It may not work immediately but after some time of chanting metta mantra, my mind gets cleansed from negative thoughts and I start feeling better.

Don't give up. You may feel horrible in the beginning of metta practice but that's normal; mind is getting cleansed from material dust. Try to understand: metta practice is a action in the mode of goodness. Like all actions in the mode of goodness, they are bitter in the beginning but sweet at the end.

Good householder. Just observe the precepts well and seriouse, change your livelihood and style so that this is possible and train yourself in generosity. Nonsens to try to fix here things by forced meditations. Metta, of course, is the base, right view, of all this simple training, good householder. From freedom of remorse, through keeping precepts, based on right view, the path develops on the given cources by "itself", including right conncentration, knowledge... insight of the destruction of effluents, followed by release from all suffering.

Silena sugati yanti, Silena boghasampada, Silena nibbutam yanti, Tasma Silam vasodhaye.

Virtue leads to happiness, Virtue leads to wealth (incl. real wealth), Virtue leads to Awakening, Nibbana, This is why we should stick to them.

A good, generouse given read in addition: The Healing Power of the Precepts.

(Note: not given for trade, exchange, stackes, or other binders to the world but for liberation of this wheel)