I fantasize about strangling a random person
Are you for real? Why do you fantasize about strangling someone?
Sometimes I think the world is too quiet, lacking the real excitement of being alive.
Both that fantasy and your reasoning are a  bit out there but as long as you don't act on it then it's fine. A lot of people have some less agreeable fantasies, it's the one who act on them that end up getting into trouble.
I know, I'm not planning on doing anything with it.
I'm glad you don't plan to act on them, otherwise it would be a serious problem. But still, your fantasy is questionable and you should be careful thinking such thoughts.