I think regular commuters sometimes are not aware of their own strength and it takes a break in the routine to bring it up. I am a middle-aged chick, can stand to lose a few.... dozen...30 mi RT trip across downtown, traffic and all, holding average between 15 and 16 mph. One morning on a weekend I set out on the MUP to explore a tricky transition between two paved sections. I found it, kept going further into the park and next thing I remember I came to the end of the trail - 26 miles out. Aack!!! Well, there is no other way but back. Came home hungry as heck, ate massive lunch and proceeded with the remaining household activities.