Today I went to El Chorro Regional Park to walk. I parked in the first parking lot, then walked to the off-leash doggie area, went in to sit down for a while (and watch doggies), and then returned to my car.
I walked on asphalt. The walk hurt my back and my left foot. My foot has a callous on the left side, which was irritated by my shoes. The total time spent on this walk was about 24 minutes, and I'd guess I took it at a pace a little bit faster than I did the treadmill the other day.
I think it's better that I stick with the treadmill or other softer surfaces, to avoid pain.
I don't publish information like this because I like to whine about my aches and pains. It is so I have a record I can look back upon.