Every day is the best day ever.
I try to improve myself every day, so I can be a better me today than I've ever been. And every day I can learn something new is the best day ever.
You might think that is statistically improbable but it is also relative. Once it's past you can tell yourself it's of no consequence, and you don't know what's going to happen in the future, so that is of no consequence either. Making each day the best day because it is the only day that matters.
Of course you need to keep your eye on the future to place your goals and you need to be aware of the past to learn from it, but the time you have is the time that is passing right now. So use it! And make it the best day ever!