I 2nd what Ananda said about joining a club.
Back to Geology, more specifically, Paleontology (study of fossils). I was also looking for some healthy activities/hobbies, and yesterday I took my first step by joining a fossil hunting club. I have not done this in YEARS (but I have a good collection from my younger days).
So fossil hunting is something I already know about and enjoy. Add to the mix hiking, climbing, the outdoors in general and no alcohol!
My first field trip is in March. I am ready now.