Life is a giant optimization exercise. And like in optimisation problems, you have to make trade offs. You can optimize only on a few out of the following variables: learning, money, time, relationships, family, career, fitness (both mental and physical), travel, love, memories.

Scaling/optimizing on one variable often leads to disappointments/ failure in others.

Example. If you are a startup founder working 100 hours/week, you might be optimising on startup success but not work life balance, including family time.

When I was a kid I used to maintain a diary where I would write the highlights for the year. Through this exercise I learned pretty early in my life about the things which made me happy. Since then I have always tried to optimise on those.