No power for what? I suppose you mean you are exhausted, but your wording does not make that clear. Proper diet/sleep and exercise help as well as eliminating whatever extra demands on your time that can be excluded. Do not live up to anyone's standard for parenting but your own. Do what you can and take care of yourself. Kids need parents for the marathon, not just the sprint.
Back to basics. Eat right, exercise and, if possible, get plenty of rest. Get your hemoglobin level checked out. You may need some vitamins/iron.