The real problem is that the pain actually gets worse. You have created massive acidosis in your muscles so there is a huge quantity of hydrogen ions and the pH in your blood changes. For 15 minutes you lie there thinking, "God, this is really bad. I'm going to die. It has never been this bad before." And every time you think exactly the same thing. You have to lie to yourself by saying you're not doing a second set. Then, without moving for 15 minutes, almost to the second, I would roll over and think, "OK, I think I can do a second set now." During those sessions I have never felt more alive or so close to death.
Recorded Cyclist, 1 January 2018 source