My heart rate goes up as I get warmer more than from fatigue. Much of the health benefit from running is also available from briskly walking a couple of miles

My heart rate goes up as I get warmer more than from fatigue. Much of the health benefit from running is also available from briskly walking a couple of miles on a regular basis. Higher intensity training builds cardiovascular capacity, but the health benefits happen at intensity levels that don't really do that.