Also, since I notice you are apparently motivated to improve your health by wanting to gain eternal life, I would figure that eternal life would be enough of a motivation. Are you really failing to find immortality emotionally moving? I can see why one would, but you claimed that was your conscious motivation. Need something else, perhaps?
There's a somewhat involved chain of causality between 'increasing the odds of immortality' and 'do another one of this painful thing', said chain involving all sorts of probabilities and estimations and outright guesses. Sometimes, that chain alone is enough to keep me keeping on. Sometimes, the odds that the effort will result in the reward seem low enough that it doesn't seem worth the cost. Thus, I'm quite open to whatever other motivations could help get over the hump.
Yes, you could get killed by a mutated pandemic, an asteroid strike, a car crash, a mugger, or a UFAI. But really, probabilistically speaking, what will probably kill you is either cancer or heart disease. Exercise prevents and fights heart disease, thus decreasing the largest single preventable mortality factor.
Eternal life is gained one year at a time! You want to make it as far as trying to tile the Solar System in copies of yours...
"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?