Missed the real skateboard by a few years, but I've been riding a bike since I was 7 pretty much uninterrupted. I'm on #8 now. I was in the first group of people to start screwing up their bike to try and get it to ride the fire roads and trails in the area. We have one of the worlds best mtn Bike Parks in Santa Rosa (200 feet to1,400 feet) most of the trails are black diamond. I'm old enough to remember when bikes had the complete run of Mount Tam, out to the coast and down to the Bridge. I go out there a few times a week, I'm not killing myself or anything, and there are a couple of trails (some of which were faint paths when I started up there, like Rough-Go, that I won't ride anymore. I can, I just don't see the point. But Lawndale trail is 2.9 miles long and goes from about 490-500 feet to 1320, it's physical climb - or a buzzbomb going the other way. And people consider mnt biking extreme, I don't. Street riding in downtown San Francisco in mid-day traffic is extreme. Climbing is extreme if you're going freestyle, not so much with ropes and safety equipment. I ski (I can ski very fast on an advanced/intermediate trails, with a smoke in one hand, a martini in the other and never miss a beat or spill a drop, I can ski harder stuff if I have to, but you have to use poles, no martini). Skiing is extreme if your going off cliffs, jumping huge cornices, running chutes in the High Sierra, skiing out of bounds or off limits, or heli, but most skiing is as extreme as a shopping trip to the mall. But I get up to Squaw and Heavenly in the winter on a regular basis. I don't climb much anymore except doing shows, sold the motorcycles years and decades ago now, and try to avoid fights when possible.
http://www.everytrail.com/view_trip.php?trip_id=655151