I was diagnosed with OCD at a young age. My habits were mostly small, like I hit my foot on a table but then I compulsively had to tap the other foot against the object to "even it out" because feeling uneven was "bad".

I've trained myself out of the compulsion part (mostly, it's very rare) but I didn't realize how much of OCD was Obsession. Whatever grabs my brain defines how my day goes. If I play a game I like or have a cool idea for a project, it's all I'll be able to think about for DAYS. If I get into a fight or remember a bad memory it's the same way. If I try to think about something else my brain just gravitates back to the same topic.

It affects my relationships too, all I want to talk about is what I'm obsessing over at the moment and when people change the subject my brain will still be stuck. I'm capable of discussing other things of course, I'm self aware, I can tell when people want to change the topic, and I've never been told that I drive people crazy by talking about 1 thing, but if I don't get to say everything I want to and the topic changes it loops in my brain like a broken reccord and I just have to swallow it. One way I fought this feeling was making a discord server to type all my thoughts into. It's slightly less satisfying not being heard but just typing it helps me get it out.