This is what I do:
- run 5x per week every morning (~30 miles a week; more if I'm training for something)
- stretch, dynamic before, static after. Essential to prevent injuries
- weight lift 3x per week (bi/tri, chest/upper-back, abs/lower-back/shoulders)
- take rest days
- sleep 9-10 hours a night, going to bed at the same time (EDIT: every's needs here are a little different)
- eat 1 salad per day
- eat lots of fruit (apples, pears, banana's, raspberries, cantaloupe, etc)
- avoid processed foods, and overall eat healthy
- keep stress levels low (figure out what stresses you and then you can manage it)
I use to be very obese (5ft 10in, 240 pounds), but lost the weight through calorie restriction about 10 years ago (6ft 0in, 160 pounds now, muscular, etc). Later I got into running which made me much healthier. That begot eating healthier, which eventually begot weight lifting. Now I can do some crazy stuff, like run up all the stairs in Porter Square. You feel like superman all the time.
The human body needs maintenance. Like a car you can abuse it in the short-run and it's still gonna run. But eventually it catches up with you. Problem is, if a car dies at mile 100,000 because you didn't change its oil often, you buy another car; but you can't buy another body.
It takes time to get into a healthy lifestyle. One-step at a time is the right approach. If you're overweight, focus on calorie restriction. If you're a healthy weight but want to get fit, pick an activity that you'd enjoy. Some people like solitary stuff (running), others like social (team sports or workout classes). If you're not eating healthy, get a book about nutrition and change your diet (Google "Nancy Clark"). You'll eventually find that one healthy step leads to another.
Lastly, keeping healthy is like having a second job. Carving out time and prioritizing it is key. You'll find that friends, employers, bosses, spouses, what-have-you, try to steal this time away from you. You've got to fight back and remember that you're investing in your future. Especially with jobs; would you rather be rich, prestigious and unhealthy, or poor, unknown and healthy? A "good" job or startup will let you be all the good and none of the bad.