I'm a pretty fit guy. I don't consider myself to be that fit, but most of my social groups have attributed that to me. Here's what I do:

• Lifting weights. Specifically, training for powerlifting and Olympic weightlifting. Developing maximal strength is the best way to develop a strong body, and a strong body is significantly harder to kill. Cardio is easy when you're strong.

• Train for specific, concrete, realistic goals in short, medium, and long term. For the short term, my current goal is fat loss, as measured by either defined abs or 180lbs (whichever comes first). After that, my short term goal will be to squat 400lbs. My medium term goal is to compete in a powerlifting meet this year, where I'll total 500kg, and a weightlifting meet, where I'll total 200kg. My long term goal is to be strong and healthy so as to prolong my life expectancy.

• Develop habits and behavior patterns that accomplish your goals. For me, this is lifting consistently and adhering to my diet. I do not think about these things -- I just do them. They're as much a habit as brushing my teeth or taking a shower, and as such, require almost no willpower.