I used to be an avid strength trainer and enjoyed working out. Recently I was injured, and now my workouts for the forseeable future include the treadmill and only the treadmill, which I deplore. I've also had to alter my diet quite a bit to consume fewer calories to account for my change in workout routine. As a result of all this, I'm having perhaps my most difficult battle with the sort of situation you are talking about -- I'm having to do stuff I hate consistently in order to stay healthy and fit (though I don't care about cryonics...).

Here are some things that work for me:

• Build a strong plan in order to make execution mindless. I fill out a 30-day whiteboard calendar with my workouts for a given month. Then I cross them out only after I complete the workouts. Then I do the workouts. My diet is of a similar strict, pre-planned nature in an effort the make day-to-day execution mindless. I have prohibited foods (fast food, alcohol, soda, dessert) & required foods (raw vegetables, raw fruits, 2 liters water, multivitamin) & a daily framework for my meal schedule. I find it help to separate the planning phase of diet and exercise from the doing phase.

• Have medium-term requirement that relies on daily requirements. I add 1-minute of treadmill work per workout x 20 workouts per month. I am only allowed to add 1 minute after each completed workout, and I must get to the forecasted requirement for the next month. Day 1, Month 1 starting requirement was 20 minutes. Day 1, Month 2 requirement was 41 minutes. Day 1, Month 3 requirement is 61 minutes, though I'll likely max out at 60 minutes. This, in effect, is a 60-day ramp-up-phase that is (a) manageable & reasonable, and (b) forms a useful habit.

• Pay limited attention to medium-term results; pay no attention in the short-term. Learn some good fundamentals on weight loss and fitness, build a strong plan you can follow, then just do it for 90 or 180 days, weighing in monthly. Weighing in (or comparing other fitness benchmarks to your starting condition) more often can be useful only if (a) you recognize how much this stuff tends to flucuate daily and (b) how much cumulative effort is needed to see significant improvement. In most cases, people weigh themselves obsessively early in a diet, lose 5 lbs after starving themlselves for a week, gain 2 lbs back after two weeks and then give up because they are hungry and discouraged 'cuz 3 net lbs wasn't worth that two weeks of hungry, cranky hell. Instead, build the good, strong plan, mindlessly and blindly execute for 90 days, then check and (perhaps) adjust accordingly.