Let’s say that from your current location, you know that the destination you want is north of you. So you say “I’ve got to go north,” and you start walking. Except, you don’t have any idea which way is north so you basically just picked a random direction.
Not only aren’t you going to reach your destination, but you also aren’t likely to discover that you’re going the wrong way for a long time. By the time you realize your mistake, you might just decide that wherever you’re headed is where you wanted to be all along and just settle there.
This is often how people treat their own motivations. They want happiness, so they say “I’ll do this thing,” but like the traveler with no compass they have no idea if that thing will make them happy. They might eventually realize that it doesn’t, but have invested so much into it that they sort of reverse course and say “this was what I wanted anyway.”
A lot of the process of discovering what makes you happy is just that: discovery. You have to try different things to a degree. But some analysis is warranted! You should at least try to think about what “happiness” would even look like, manifest as. What does a day of your life feel like if you’re happy? What things would disrupt that? This is sort of like looking at the sunrise to get your bearings; at least have some sense of direction.
And don’t be afraid to turn back early. If a little of something didn’t make you happy, a lot of it isn’t likely to do so.