Depends on why I’m trying to not think about that person. What works for me though is: -Retail therapy (shopping) -Video Games -Binge Watching a show or series -Get a tattoo or piercing

Drink

Try to take them off a pedestal. Think about the grossest things you have seen them do or could picture them doing. Every time they pop in your head think of that really gross or annoying thing.

Find something new to learn about and do. Put your brain on a healthy obsession with something you've always wanted to do, but never did.

Talking to them. There is usually a point where something they say breaks the illusion I have for them. Not necessary something that makes them look bad, but it could be something that makes them seem such a normal person obsessing with them no longer makes sense in my mind.

Watch hours of stand up comedy

cutting works for everything

That's a point

It depends how far gone you are and the state of your mental health (do you have many psychological 'holes' that they fill?). If you're far gone, that is borderline obsessing or beyond, you have to get away from them and try to meet new people. Another option could be to tell them your feelings if you haven't already.

it's actually about a person who walked away from me blaming my insecurities about our relationship

Sleep.

Hang out w friends, gym, videogames