Building your Qi
You can focus on diet, lifestyle and exercise, all really good. But I think there's a better way at looking at it. Instead of looking at all the things you need to do or should do, look at your qi, look at your energy. What builds your qi, what disperses your qi? If you can spend your days building your energy then when you need it it's there for you. So rather than thinking about food being good or bad, or exercise is good or bad, just notice how it makes you feel on a deep level, on a subtle level. What happens to your energy? Is it building your energy? Spend your days building your qi so it's there when you need it.