Honestly I don’t do anything to maintain it. I don’t exercise, I eat inconsistently, as in I eat a combination of unhealthy things with occasional healthy things and my appetite changes. I have had a fast metabolism my whole life (it has slowed down over the past couple years though). I am not perfect but I’m content. The only reason I do keep trying to change my habits to be healthier is to feel healthier. You just have to find what works for you because everyone’s body is different.