Because eventually, every round will be become a hard round.
If you walk head first into a challenge, you have already won. Whether you “win” or “lose” the exchange is secondary.
There are going to be hundreds, if not thousands, of hard rounds between you and whatever your goals are. You might as well get started immediately.
As an athlete, I was usually on a strict training regimen — meaning I had quotas, spreadsheets, and all of that.
In the “off times” where I was moreso training for fun, I still had one rule: do every round that I want to do, and when I feel like I want to quit, I always did one more.
I think that’s a pretty simple way to maintain discipline and ensure progress.