If you want to improve your health by making better lifestyle choices ,what are five choices that you could make?

You could eat healthy everyday, exercise, drink at least 6 to 8 cups of water each day, get enough sleep, and try to put less stress on yourself. :)

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.