Yesterday is history, tomorrow is a mystery, today is a gift. That is why it is called the present.
There have been many versions of this quote throughout history, but as a huge Kung Fu Panda fan, I like to attribute it to the venerated founder of The Valley of Peace, Master Oogway. In the first movie, he introduces the quote with a brief admonishment to Po which is deeply related to the popular wrestling concept of surrendering the outcome: “you are too concerned with what is and what will be.