When you get to the end of your life, old and tired, and you look back on all the things you did and time you spent, what will make you say: yes, I did well and it was all worth it?
Put another way, if you have an extra hour tomorrow with nothing planned, what could you do with yourself to later say: I’m glad I did that? What if you have an unplanned day? Or a week? Does how you use that time change? Would the choice of how to use that time be more or less deliberate, depending on how long you have? Does that choice define you as a person?
What a great thing to do! I think it's why a lot of people volunteer for causes and give their time and money to charity. Such a great way to directly see the positive impact you're having on the world.