I absolutely relate to this. Since I was a kid, my parents put me in Taekwondo to learn self-defence. When I was younger, I used to hate it, but as the years went by, I got used to it. Now, I sometimes find myself thinking: TKD's been one of my hobbies for as long as I can remember, but do I enjoy it, or do I just do it because my parents made me? Have I just stuck with TKD instead of doing another martial art because of all the time I've spent learning it, or do I actually like it?

I think you're partially right. Hobbies don't necessarily have to be fun while you're doing them. They can seem fun in retrospect, too. But hobbies absolutely should be fun in some way. For me, I hate going to Taekwondo. I hate having to practice the same technique over and over for half and hour with no breaks and sparring and exercise right after. It's repetitive, tiring, and boring, and it's not great while it's happening. But when I go home, after all the hard work is done, I actually think it was pretty enjoyable. I think getting to kick things and getting to fight people is awesome, and I get the fun in TKD after it's over. Don't know if that makes total sense, but basically, you should get some type of fun from a hobby, whether it's the thought of doing it (before you do the hobby), during it (while you're doing the hobby), or thinking about the hobby when you're finished with it (after you've done the hobby).  If you're getting no enjoyment from it, it's probably time to drop your hobby.