Two Things That Will Make You Feel Good

There are two things that always make me feel good: service and exercise. When I was younger I always saw exercise as drudgery, but now my views have changed. It may be due to the fact that now I choose to exercise, and I do what I want to do, not what the P.E. teacher told me to do. Another reason may be that instead of giving me stress, it relieves my stress levels (scientists say that exercise uses the cortisol released under stressful circumstances, which is why it feels good).
Exercise also releases endorphins--little molecules of goodness that bind to receptors in the brain, causing one to feel happy. Added to all this magical chemistry in the blood and in the brain is the feeling of success that one gets when winning a match or a game in competitive sports.
Since I didn't know of a physiological reason why it feels good to serve others, I decided to look it up online and see where the sea of the internet took me. I ran into an article in the Washington Post that reported the results of brain scans of individuals performing good deeds to others. It turns out that doing something unselfish activates a primitive part of the brain that usually lights up in response to food or sex. Altruism, the experiment suggested, was not a superior moral faculty that suppresses basic selfish urges but rather was basic to the brain, hard-wired and pleasurable.
The observation made me wonder why, if we are hard-wired to do good, is altruism so rare in our society? Does our culture and society train us to ignore those "basic" functions? Do criminals have lesions in their "good deed center"? Hopefully more research will be done on the subject because I would like to know....