For a while now I have been biking with a group of people every Sunday. We pick a different trail each week and encourage those that are new to mountain biking to join us. No better way to learn something than to have 10 or more people willing to help you at anytime. Recently I joined another group that rides on Saturday mornings happily experiencing the same situation. The first ride for me was today and I met 11 of some of the nicest people.
If it isn't the thrill of something that brings you back to it, then hopefully it is the good friends you meet along the way.