I got serious about meditation in my twenties, but now do it rarely. My most recent experiment in self-improvement (more physical than mental) was to switch to a plant-based whole-food diet (keeping to it about 95%+, with few indulgences).

I do feel much better: Improved mental clarity, energy level stays more constant through the day, and gastro-intestinal tract has never been better. Between the diet and exercise I'm hoping to delay the inevitable decay of old age. Will hit 60 later this year.