I can't.
I seem to have a very definite exertion level that is less than the average. I can do low level aerobics forever. Medium level for about an hour. High level for a few minutes, before I can't push through anymore.
After that it is asthma attack and seeing stars.
When I was 21, and seemed in absolutely perfect shape, it annoyed me and I tried to fix it. I went to the gym at least once, but often twice a day and ran flat out, fast as I could, until I saw stars and thought I would pass out.
I'd never get over an hour of light jogging, and I'd certainly never finish in a respectable time.