What you can change is what you can do tomorrow, what to study, listen to, what to read, who to meet, ... And what do you want to create next in your life.
And what you want to correct with those mistakes that you've done in the past.
The past can't be changed and we can no longer go back there if we want something to change or the wrong decision that we've committed. We need to move on and look in the present and future.
Doing the right things is what we should do instead.