What’s the hardest set, mentally or physically, you’ve ever done or given?

In 2009, I put my swimmers through a grueling set of 50 flys with push-ups and pull-ups in between each one. This was after a dual meet between Auburn and Texas that didn't go well for us. It was an illegal practice, but you can find videos of it online if you google "float swimming Auburn practice 2009".
 
Transcript: "Henry, 2009, we actually had a dual meet Auburn versus Texas in January of 2009. And at that time, I felt like our team underperformed. They really didn't give the effort I felt like they were capable of, and Texas ran over us in our home pool. And after the dual meet-- the dual meet went for about two hours-- everybody competed, raced all the full events. We went outside in the long course pool. By that stage, it was nighttime. It was getting cold because it was January, and we did a little practice out there that I would say was probably the toughest physically and mentally that I've ever given anybody. What we ended up doing was a set of 50s. From the block, you had to dive a 50 fly. And then you had to do some push-ups at the end of the pool. And then you had to run back. And we had a set of pull-up bars. You had to do a set of 10 pull-ups. And then you had to get back on the block and do a 50 fly. And we just kept repeating this. We didn't give them a limit on how many we were doing, but we took them to the breaking point. There was some really interesting things going on. I don't know how legal it was at the time in terms of-- I don't think you're allowed to do practices at the end of dual meets but something that we did. I even think you can look it up. It's on the internet. If you go to like a float-- I think float swimming was there and they might have put it. So if you google in like you float swimming Auburn practice 2009, you might be able to find this thing out there. But it was one of the craziest, funniest, toughest sets I've ever given."