A popular and successful way to do this is to start hosting a regular potluck. All you need to do is get the word out and have a regular time for people to show up. Whether you join or start a group, or even just want a less formal approach to finding people, you still need to figure out how to locate such folks. In most cities, these days, you can find a food co-op or health food store that is a focal point for people with similar interests. Most of these stores have bulletin boards where you can put up a simple sign, looking for your new friends.
Local churches are often a great source of finding people interested in simple living.
You don't have to agree with the specific tenets of the church in order to find good like-minded people. While the university may not be the source of the group you might want, they often are great resources for knowing what other groups are in the area. It's a good idea to prepare yourself so as not be worn down by reactions to your efforts. One tip that I've found useful is to consider yourself an educational resource. This is not to say that you should necessarily start proselytizing to all of your friends about how important it is that they live the way you do.