Hi CC8,
Hiking's a good option. See if there's a local chapter of the AMC in your area. Also, the sparkpeople website has a sober section with all kinds of meet-ups and activities for a healthy lifestyle.
I keep busy with my kids and studying. Right now, however, I ache all over from playing with them yesterday. At 52 I think I need gentletr hobby - like lying in hottubs!
Best of luck and be careful. A friend of mine had 8 years and felt like you do and went right back to shooting dope. The difference is he never told anyone how he felt - you've done that and moved in the right direction. Stay strong - sober's better.
Mike in Boston