Yesterday doesn’t matter when you consider what you could do today. It doesn’t matter if you’ve lost the game 100x in a row. That was yesterday and today is a clean slate.
You can take your clean slate each morning and fill it with regret from what you didn’t do. If you do that, you are filling your potential for the day or even the hour with bad stuff that only sets you behind.
You put yourself into a sort of social debt that only makes work right this moment more difficult. Forget the failures and shortcomings of yesterday, they make everything more difficult today.