Do I Feel Great!

Along with the interval training approach, I spent today walking at a constant speed.  After eleven minutes warming up (2.5 MPH, then 3.0, then 3.5), I walked for nineteen minutes at 4.0 MPH on the treadmill.  My pulse varied between 108 and 143, but at no point was I ever tired or in any discomfort.  I could feel that this was demanding -- but I did not break a sweat.  I am convinced that I could walk at 4.0 MPH for a couple of hours without problem.  For a man of almost 57, and one carrying about 30-40 more pounds than I should, I feel pretty darn good.