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.
If I might ask, do you know of any related online fora that are reasonably friendly to people who are just starting out with the whole 'exercising' thing?
Partly due to your post, I've just bought some adjustable wrist-weights to make toe-touches and similar exercises more productive, but I'm operating with a very small relevant knowledge-base.
"Cryonics has a 95% chance of failure, by my estimation; it would be downright /embarrassing/ to die on the day before real immortality is discovered. Thus, I want to improve my general health and longevity."
That thought has gotten me through three weeks of gradually increasing exercise and diet improvement (I'm eating an apple right now) - but my enthusiasm is starting to flag. So I'm looking for new thoughts that will help me keep going, and keep improving. A few possibilities that I've thought of:
Pride: "If I'm so smart, then I should be able to do /better/ than those other people who don't even know about Bayesian updates, let alone the existence of akrasia..."
Sloth: "If I stop now, it's going to be /so much/ harder and more painful to start up again, instead of just keeping on keeping on..."
Desire: "I already like hiking and camping - if I keep this up, I'll be able to carry enough weight to finally take that long trip I've occasionally considered..."
Curiosity: "I'm as geeky a nerd as you can find. I wonder how far I can hack my own body?"
Pride again: "I already keep a hiker's first-aid kit in my pocket, and make other preparations for events that happen rarely. How stupid do I have to be not to put at least that much effort into making my everyday life easier?"
Does anyone have any experience in such self-motivation? Does this set of mental tricks seem like a sufficiently viable approach? Are there any other approaches that seem worth a shot?