Buddhist practice and physical exercises

The mind is no different than the body. The state of one has a direct impact on the state of the other. If you are out of shape and inflexible, you simply won't be very well prepared for sustained mediation sessions. You are either going to fall asleep on the cushion (i.e. sloth and torpor) or your back, your legs, and/or your hips are going to be in agony. You certainly won't be able to maintain the upright and invigorated positions necessary for deeper mediation.

Don't get me wrong, some discomfort is inevitable. In fact, a little discomfort is even encouraged. But why compromise your sits when you can do something to combat the grosser disturbances that an out of shape body could cause? Obviously, don't go overboard with it. You also shouldn't select exercises that could cause you difficulties on the cushion (heavy back squats are just one example). You aren't clinging to the body by exercising. You are maximizing the benefit of the time you spend on the cushion!

And let's not forget - some taoist yoga, Vedic yoga, and Shaolin kung fu were all [to one extent or another] designed to bolster meditation practice!

Exercise can be healthy or delusional according to your intentions. If you believe that bodies can be beautiful and having a beautiful body (or a body that is somehow different than it is) will bring you true happiness; than that doesn't really accord with true happiness in Buddhism.

If you're trying to stay healthy to have the energy and vigor to study and practice with ardor, what could be wrong with that? Unless you go overboard and lose your wholesome intention of course.

One thing about sitting at work; see if you can possibly switch up your work station to stand. I did this 10 months ago and it feels very energizing. (I'd rather spend my sitting time on a mat at home!) If your employer is open to the idea, some creative re-arranging of your work station might be easier than you think. Best wishes.

Health is the greatest gift, contentment is the greatest wealth, a trusted friend is the best relative, Nibbana is the greatest bliss. - Dhammapada 204

For a lay person, moderate exercise, moderate diet and good hygiene can be considered as part of the middle way that the Buddha taught in the Dhammacakkappavattana Sutta, as it contributes towards the maintenance of one's health, which is beneficial to practice. You also cannot practise Right Livelihood without good health. The purpose of Buddhism is to escape suffering. And with poor health, you would only be causing suffering for yourself.

"There are these two extremes that are not to be indulged in by one who has gone forth. Which two? That which is devoted to sensual pleasure with reference to sensual objects: base, vulgar, common, ignoble, unprofitable; and that which is devoted to self-affliction: painful, ignoble, unprofitable. Avoiding both of these extremes, the middle way realized by the Tathagata — producing vision, producing knowledge — leads to calm, to direct knowledge, to self-awakening, to Unbinding.

On the other hand, excessive exercise either for vanity or as an addiction (see here and here for the case of running addiction), are not considered skillful. In case you are afflicted with exercise addiction, the Buddha has a remedy in the Sukhamala Sutta:

"Even though I was endowed with such fortune, such total refinement, the thought occurred to me: 'When an untaught, run-of-the-mill person, himself subject to illness, not beyond illness, sees another who is ill, he is horrified, humiliated, & disgusted, oblivious to himself that he too is subject to illness, not beyond illness. And if I — who am subject to illness, not beyond illness — were to be horrified, humiliated, & disgusted on seeing another person who is ill, that would not be fitting for me.' As I noticed this, the healthy person's intoxication with health entirely dropped away.

In the case of monks, the Buddha explains in the Sukhamala Sutta:

"Drunk with the intoxication of youth, a monk leaves the training and returns to the lower life. Drunk with the intoxication of health, a monk leaves the training and returns to the lower life. Drunk with the intoxication of life, a monk leaves the training and returns to the lower life."

Despite this, I can still find some example of a monk trying to get light exercise, in the Meghiya Sutta (below). This leads me to think that light exercise without "intoxication of health" might still be considered acceptable to monks.

Then in the early morning, Ven. Meghiya adjusted his under robe and — carrying his bowl & robes — went into Jantu Village for alms. Having gone for alms in Jantu Village, after the meal, returning from his alms round, he went to the bank of the Kimikālā River. As he was walking up & down along the bank of the river to exercise his legs, he saw a pleasing, charming mango grove. ...

It is ok(ethically) to do physical exercises even for the purpose of being attractive. Lay people are not expected to follow the rules of monks. Such conflicts occur mostly when you try to live a monk's life as a lay person. Is it clinging/attachment that motivates you for physical exercises? Absolutely! But it's similar to asking if it is ok to have love affairs or get married. They all involve unwholesome mind states. But you are mostly expected to keep to the 5 precepts as a Buddhist layman. So you should focus more on the 5 precepts as they can be easily broken if you are not mindful. If you want to live a more noble life, you can get ordained. Things become conflicting and confusing when you try to walk on the fence, not picking either lifestyle.

In fact, it is clinging that makes you do the job you do. It is clinging that keeps you in lay life. If you don't have clinging, you can't live as a householder. You have to go get ordained within 7 days or die(parinibbana).