I agree! My friends who don't ride (in fact they are totally sedentary) think my husband and I are crazy. I could easily stop calling them, but it seems rather immature of me to do this, at age 51. We have become friends with another couple who rides and have many other similiar interests.
Totally totally agree and understand! Many of our friends just don't get hubby and me either. We also just bought touring kayaks, which puts us even more "out there" among our longer-time friends. I wouldn't say our friends are sedentary, but they spend all their leisure time working on their yard and houses. They walk, but don't do any serious exercise. My husband I and lift, road ride (including organized centuries and events, club rides, etc), hike, bike tour, travel, and just recently got mountain bikes and kayaks. VERY different lifestyle! Fortunately, we've also made new friends through our bike club that totally get it.

On the other subject, I just started mountain biking last fall. It is different and for me takes total concentration. In fact, it scares me to death, but afterward, I feel like I have really accomplished something. I need to get better, though and it looks like the trails around here won't be clear and semi-dry until late April. I wouldn't say I totally relax or zone out on the road, it's just a different feeling. I think it's good to do both. I don't think mountain biking will ever be the focus that road cycling is for me, but it teaches different skills and extends the season by at least a month because you can mountain bike up through December even here in New England.
Once again, I agree totally! I find mountain biking very tough and a bit scary - definitely an adrenaline rush. I can't do it for long, but I do feel that it is great for fitness (upper body as well as lower), balance, and bike handling skills. We live on 11 acres of woods, into which my husband has put in over a mile of trails, so we can mtb right out from our door, where it takes awhile to get out to the road (just the opposite of most people!) since we live down a long gravel road we can't ride our road bikes on. It's nice to have a close place for a workout when one has less than an hour to ride (say, after work). I also like it because I can do it when it's too chilly or windy to ride the road. I get so hot mountain biking that I can manage it at much cooler temps.

Emily