There is also the physical satisfaction of muscles well used, strengthened for another day's use, lengthened lifespan of healthy enjoyment. I feel so good when I really work my body. I hate gyms and monotonous, routine workouts with no goal besides physique/cardiovascular benefits. They are great, but it's so boring. Working with a purpose besides selfish* endeavors is much more satisfying. *I have a hard time saying it's selfish when it's so beneficial to everyone in society, from coworkers to family members, for you to be in good health. Maybe wasted potential is a better way to put this.