If you implement these few instructions in your life then you will be fit and healthy:
1. Have Breakfast
2. Drink Plenty of Water
3. Take an Exercise Break
4. Go Offline and sleep on time
5. Learn Something New(New skills help keep your brain healthy)
6. Don't Smoke
7. Train Your Muscles
I think # 3 & #7 are the same thing. I also would add getting some sunlight into the mix. Some sort of social interaction is never a bad idea either. Even if it's just a phone call or quick Facetime with someone you are friends with (not work stuff). A positive attitude and a daily dose of helping someone else can do wonders for one's attitude as well. Most importantly though is just to make an effort. If you don't take that first step towards being a healthier person, you never will be.