You get very tired, and there was a certain amount of pain and you slow up. Your legs are so tired that you are in fact slowing. If you don't keep running, keep your blood circulating, the muscles stop pumping the blood back and you get dizzy. ↗
But you've got to have money for comfort, which obviously doesn't matter as much when you're young, but even so. I always like to bloody eat well and be warm. Have a drink when I want it. ↗