How do you "build energy"?

I take vitamins and try to do physical exercises. For me it helps to write down how often I do physical exercises and other healthy things like food-intake and sleep. I use two apps for that, Daylio and HabitBull.

When I can track important events during the days, I feel more relaxed with how much energy I can expect. My experience is that it takes me from 6 - 8 weeks to build enough energy if there has been weeks without gymnastics and so on. Lesser if the down part has not been so long, but we are all different of course.