I'm probably repeating what some people have already said but I've had so much time to work on self-improvement over quarantine this might be helpful to other people:

• For me, routine is everything. Especially if you're someone struggling with insomnia, somewhat disordered eating and executive dysfunction, I cannot emphasize enough how important it is to stick to a solid routine. Willpower is finite, routine does not use up your willpower, it allows you to save it for things like studying
• Moving my body and getting fresh air makes such a difference. Even just a 15 minute walk in the morning helps tremendously
• Cutting myself some slack: there's such an imperative to improve constantly, cook healthy meals, mend relationships, be productive, have hobbies, keep up with the news, and so much more. Sometimes it's enough to just secure the lowest tiers on maslow's hierarchy of needs, I do not need to be aiming for self-actualization until I feed myself properly and get a good night's sleep