@theunkowndeity: Every list like this is wrong to somebody. Ask a rower and they'll tell you nothing on earth touches a 2k. Ask a wrestler and they'll laugh at the rower. Ask a boxer and he'll wonder why anyone's debating it at all. The honest answer is that hard means different things. Some sports take your knees. Some take every Sunday for twenty years. One of them takes your memory. The strange part is how many of these people are neither famous nor rich. They just decided the pain was worth it and went back the next morning. Go on then. What's missing? #sports #boxing #rowing #mma #cycling