Try changing a small thing in your day-to-day routine, with the aim of improving some aspect of your life.

For example, you could try cutting-out a certain food-type (whilst maintaing a nutritional balance, of course), or going to bed/waking up earlier/later.

If you take a scientific approach, and perform some before/during/after analysis, you should be able to gradually (and quantifiably) improve your life through a series of these 'experiments'.

See the wikipedia article at:

http://en.wikipedia.org/wiki/Self-experimentation