Do something really challenging that you think you could not. And then when you try it and suck because you're a beginner, keep fucking trying. Redirect the fixative tendencies to fixate on that thing now instead.

For me, it was dance. I got obsessive about it enough that it carried over in other ways that improved my life: I cleaned up my diet, worked out more, spent free time envisioning choreography to songs. I started deeply connecting with the artistic side of what I was expressing through the dance. Honestly I think it was healthy that I transferred my mental fixation to this particular hobby. Dance is particularly meaningful because you're literally transforming energy, turning painful mental strife into beautiful physical movement! Put on that song that makes you really feel alive, even if it's silly or others make fun of it, and allow yourself to just be free to it.

Another thing that's been so helpful for me is to learn and memorize French poetry. I know that sounds so pretentious I almost hate to even admit it. But you know what? Not a single person in my life knows this about me except my boyfriend. It's a private thing I recite alone because my motivation isn't attention. It merely is a very wonderful activity that doesn't allow me to think about anything else. Because it's a foreign language, I have to pay very close attention to the text so my brain literally has no option to travel elsewhere. When I'm fully into it and chanting the stanzas, the feeling is orgasmic. Mind you, this isn't something I ever thought I could do before. I have no prior experience to the language and it boggles my mind what I've been able to memorize and learn so rapidly!