Is it possible to make an oath to control one's actions?

It is possible to make an oath (some people do), and for some people it (making an oath) even actually works, but other people find they break the promises which they make to themselves.

A possible variation is to make the oath to someone else (a teacher, your family, a friend, the Buddha) -- that (social standing, commitment) may provide a powerful extra incentive.

I think the suttas say that the right way is to clearly understand the disadvantage of something -- it's that that would cause you (or that would give you cause to) refrain from it.

You mentioned "I decided to not do anything for fun"; it's also said that people need a reason for doing something, that you can't force yourself to do it unless you want to. Maybe you're supposed to find or experience some benefit in meditation. Maybe too you have to be discerning about what is and isn't fun -- some people (perhaps mistakenly) find drinking alcohol to be fun, for example.

Generally, it is important to view the precepts as training rules, rather than something set in stone. Right speech, for example takes active practise, and of course constant reflection on it. You will fail short of your ideals because past mental formations are still lingering and are too strong.

Moreover, it's always best to have a flexible, non-dogmatic, non-extreme outlook with regards to falling short of one's aspirations. With flexible I mean that even though you have (strong) wishes and goals, they must not necessarily be in place right now & that you can - although being a struggle - tolerate such adversities, and that it's often worth to tolerate the uncomfort because you have a goal in mind (especially if you are indecisive whether to breach a precept or not).

Another "flexible attitude" is that of human fallibility,complexity & uniqueness. All human beings are making mistakes, and that we're all by default complex and unique. By complex I mean here that we're doing good, bad and neutral acts. There is no way in disputing these things. They are undisputable and therefore realistic, or flexible.

Above said, the Buddhist path is often called the "Gradual Path", which requires energy (viriya), enthusiasm (chanda) and cultivation (bhavana).

It looks like your problem is that you want to practice but you don't want to practice.

This whole fiasco can be pondered. The whole thing is the three characteristics manifesting. Are you in control? Do your plans and focus keep ending? Are you suffering? What are you learning? Ask yourself what you are taking for granted.

You could learn a lot by just pondering what is driving your every action, your karma.

We are either distracted or mindful.

Check out the 5 hinderances that are in your way.

Don't make vows or oaths but instead undertake training to not do or to do X and if you fail ponder it but don't react like breaking the training rule must be punished or reacted to is some way. Don't get angry, get compassionate.

Check out how to overcome procrastination. LOTS of people have procrastination problems. There are a lot of free pdf's or ppt's online about procrastination.

Do not smoke marijuana everyday because it often zaps ones ambition.

I know what you mean about oaths. It is easy to make an oath but usually less so to keep it. Often an oath is an aspiration. I suspect that nobody can be sure to stick to an oath except those who don't need to make one. The idea of the practice is to transcend the need for oaths and to live spontaneously but to reach this point one usually has to make some aspirational oaths.

You might like to read up on Indian religion and the three Gunas. It seems you might be in the grip of one of them and this is a well understood condition. Pondering on the three gunas might give you a way of beating your inertia. I don't know a short introduction but Krishna Prem's wonderful commentary on the Bhagavad Gita covers the ground.

I imagine most practitioners make and break oaths and promises quite regularly but their oath is to keep climbing back on the wagon come what may, so that in the end the oath may still be effective.

For your condition Sadhguru recommends sitting in your room doing nothing for a few days. This charges the batteries and rekindles motivation. Usually we are too mentally busy and well-entertained to stay focused on our true goals.

It seems a mistake to stop doing anything for fun although it might depend what you mean. Why else would the universe be here but for fun? Even God gets bored sitting in his room. If you associate fun with creativity then it is transformed. Not having fun is not what Buddhism is about.

At least your problem is extremely common so is much discussed in the literature. I don't believe it is possible to control ones actions fully until one has seen the non-existence of self and it is a reality. Until then we all have to do the best we can and falling off the wagon means no more than than having to climb back on again, and again and again, until our oath is fulfilled and the wagon becomes our stable abode.