(Previously in this vein, World Cup category.) Last summer my wife and I went to the Legg-Mason tennis tournament in DC, early in the week's play. By far the best part of seeing any pro tennis tournament in person is on the first couple of days, when you don't have to sit in the stadium seeing matches from a distance but can wander around the side courts and see players from a few feet away.
At one of the practice courts, I saw what seemed to be an absolute giant warming up with a partner. It was Isner, whom at that point I'd never heard of, and some also very tall Eastern Europe person. I was able to stand directly behind the fencing -- that is, 20 feet behind Isner's opponent as he waited behind the baseline to deal with Isner's incredible serve. On TV it is really hard to get an idea of the velocities, reflexes, and different-from-the-rest-of-us skills of top-level athletes. I watched Isner wallop serves for about an hour and was amazed that anyone could touch any of them. He is said to be 6'9" but appeared to be about 11'2", hitting serves more or less straight down. Here is pretty much how it looked.
Ten hours' worth (and counting....). Wow. No larger point.