I would say a rather strange thing: you need to make friends with yourself. You get to know yourself better => treat yourself like a friend => in difficult times you can imagine what words of support you would express to a friend. That is, to myself.
There is a good TED talk about emotional hygiene: https://www.ted.com/talks/guy_winch_the_case_for_emotional_hygiene?language=en, as far as I remember, I got this habit from there
helped more time alone. Long walks and many podcasts on completely different topics, followed by an analysis of the author's opinion. As a result, there are many new thoughts, many observations of one's own reaction. I began to understand better what to do to lift my spirit on my own :)
Unfortunately, recently it stopped working. So even in my single case, it did not become a panacea. But the habit of being friends with yourself helps to go through a lot and not go into self-destruction mode.
There is only one known case in the world when a person supported himself and at the same time achieved a good result, namely Baron Munchausen (he pulled himself out of the swamp). He also brought a working recipe for self-support: you have to drag yourself by the hair. Well, if you don’t mock, then ... then either the baron’s recipe, or abandon this idea. But everything is far from so tragic. A person does not need to support himself, a person needs to have enough strength to fulfill some action. The meaning is not in self-support, but in strength. Ie. the question boils down to "how to get stronger." Sleeping, taking a bath, eating are ways to become a little bit stronger for a short time. Going in for sports or dancing, completing specialized courses, gaining experience in some area are ways to become stronger for a long time. Although, of course, the methods I listed should not limit yourself, and there are still other equally suitable ways.
And all this fuss with support ... you have a choice between walking with crutches, and walk without crutches. Yes, with crutches less energy is spent, but walking without crutches is better.
At first, just have a good rest. Get enough sleep, do what you wanted for a long time (even if there is a lot of workload, try to find time to rest). This is necessary to relieve the head.
Then, with a fresh mind, think about yourself, just about yourself. About their positive qualities, about their achievements, about their skills, about successfully solved problems. In short, all the good things that you can remember about yourself. Understand how good you are and what good things you deserve.
And then the most difficult thing is to stop comparing yourself with others. It doesn’t work, it’s not motivation, you’re not proving anything to anyone. Learn to reasonably neglect the opinions of others (I'm talking about the example when you take on something new, and everyone tells you that oh, it's so difficult, you can't cope, and now you start to think that if the truth is not cope, they will look at you somehow).
And find the goal that is important to you, and then the question of how to support yourself will be automatically resolved. Because you will understand that you are doing it for yourself, that you enjoy doing it. This can take quite a long time, because from childhood we have been compared with someone, you cannot get rid of the habit of comparing yourself to someone completely, but you can try to minimize its influence. And yet, no matter how trite it sounds, use what you know about yourself. That is, your real capabilities, your energy supply, and so on.
This is not about a one-time action, but about a process. There is no such thing that all your life you did not support yourself, and then you do.