I prefer to work like a catalyst. I pull in energy from the earth, charge it within me, and push it out to control it. I don't become exhausted this way, and in fact, I'm usually more energized by the end of my work. With this method you definitely need to eat and drink something afterwards (I'm usually hungry by then anyway).
Remember to always give back in other ways. Even tending your own garden, planting a tree, or performing a dedication/honoring ceremony once in a while will keep an even give and take.