One important similarity between exercise and meditation is that, in both cases, growth comes from overcoming resistance. For example, when you are weight training, every time you flex your biceps in resistance to the weight of dumbbells, your bicep muscles grow a little bit stronger. The same process happens during meditation. Every time your attention wanders away from your breath and you bring it back, it is like flexing your biceps— your “muscle” of attention grows a bit stronger. The implication of this insight is that there is no such thing as a bad meditation. For many of us, when we meditate, we find our attention wanders away from our breath a lot, and we keep having to bring it back, and then we think we’re doing it all wrong. In fact, this is a good exercise because every time we bring a wandering attention back, we are giving our muscles of attention an opportunity for growth. A second similarity between exercise and meditation is they can both significantly change the quality of your life. If you never exercise and you put yourself on a regular exercise regime, a few weeks or months later, you may find many significant changes in yourself. You will have more energy, you can get more stuff done, you get sick less often, you look better in the mirror, and you just feel great about yourself. The same is true for meditation.
Tan, Chade-Meng (2012-05-10). Search Inside Yourself: Increase Productivity, Creativity and Happiness [ePub edition] (Kindle Locations 550-560). HarperCollins Publishers. Kindle Edition.