You’ve received excellent advice so far.
For me, small low glycemic meals every couple of hours helps me maintain blood sugar and energy levels on the nutrition side.
One thing that hasn’t been discussed yet is what you’re doing for mental / emotional restoration. Your brain needs a break. Meditation or deep breathing can do wonders for stress and when that’s better under control we can feel more energetic. That’s a long term strategy. A good short term strategy is that I sit in my car for 2-5 minutes before entering the gym and I think about my purpose, the gifts I have to give to the world, that I’m lucky to be in this moment, and that I will give this class or this client everything I’ve got.