In addition to all the great advice on this thread, how many hours a week are you working? If you can try to cut back down to 40 for a while.
What do you do for fun? If you're in a strong burnout it might be hard to answer. If you can get to make it your hobby to find something fun to do or reconnect with something fun you used to do.
Video games, hiking, writing, painting, drawing, playing an instrument, going out for a coffee or having a video call to an old friend can really help.
It's been written elsewhere but find a therapist and take care of yourself. Try to do 15 minutes of intensive cardio or 30 minutes moderate. Eat a good meal.