Go riding and you find it. 10 miles each way on the road going to work and back; get home and switch to my mountain bike; set off into the rain. It was an awesome mid-week adventure: hauling my way through boggy mud and clay. Normal climbs verge on the impossible, singletrack becomes streams and a ride near home becomes something remarkable. OK, it all went wrong when my brakepads wore out over 15 miles from home, but I'll quite gladly give 9 miles on the road for the feeling of doing something out of the ordinary and the sheer joy I felt when I could see the lights of Risborough up ahead.
Go ride a bike :)