If you live to be 100 years old you will spend the first 50 years of your life doing many things.
You will spend the next 50 years doing more things and reflecting on all of those things that you did in your first 50 years.
Toward the end of those 100 years of fruitful living you will spend a good deal of time continuing to reflect and evaluating those 100 years of life.
So, make sure you spend time doing the things that are worth reflecting on and that bring value to you and to others.
It is in so doing you will find happiness in a life that was truly worth living.