Sometimes you are going to have to tell people “no”. Sometimes those people are going to be your friends, or the ones that you love most. If they truly care about your well-being, they will understand and won’t hold grudges.
Live your life how you want to. Don’t let things pile on to the point that you cannot complete your important, must-do tasks. This doesn’t mean to never let a friend convince you to go out when you really don’t feel like it. But if you truly feel that you will be better off in that moment, and in the future, for saying “no” to requests, meetings, outings, favors, etc., then say it. No matter how hard it might be.