Of course, it makes sense to learn what makes you happy, but lots of people don’t. Let me focus on just one aspect, the financial one. I have spent much money on stuff that did not add to my happiness over the years. I know of many other people who also have done this.
Often there is a hope that spending money on this or that with enhance your happiness, but very often it does not. Pay attention to how you spending affects you. Though, perhaps one should not be too harsh and judge something to early. Sometimes it takes time to fully understand the impact. Also, what may bring happiness now, may not in the future, and vice versa. Always be on the lookout for new opportunities.
In short, know yourself.