I had never understood what was so great about running until I started running trails in the Santa Cruz Mountains. I used to run a bit when I lived in Palo Alto in the 80s and in NJ in the 90s, but I never really took to it, and knee injuries (from skiing) made me wary of the impact. I hate running on a treadmill, the constant stride really bothers me. But now, I can't wait for my next trail exploration. I don't run as fast as on pavement, but it's still a much more engaging experience. Like backcountry skiing compared with lift-skiing groomers. Today I ran (and walked a couple of steep pitches on the way back) from the Monte Bello parking lot to the preserve gate to Stevens Creek, and back, just under 9 miles. It was slow (just under 12 minute miles) and demanding (almost 2000 vertical ft of climbing according to my phone GPS, but I suspect it's quite a bit less than that, GPS is bad for elevation changes, I should have used my altimeter watch but forgot -- next time). I'm a bit sore, but I can't wait for the next run.