I find myself flexing my core sometimes when in public/walking. Just feels good. Plus a lot of the exercises I do you are supposed squeeze/feel your core when do them sometimes. Feels good idk.
Also, I don’t think sucking in your stomach is bad… that’s called a vacuum to some people, I don’t do it often but sometimes I do vacuums, where you basically suck in your stomach because it’s a sort of exercise for the ab muscles lol
i dont. i read it was really unhealthy for breathing. you can teach urself to stop doing it by putting a hand on ur stomach and a hand on ur chest and breathing. ur stomach should move. also ur shoulders shouldnt lift when u breathe. if u practice it enoigh u can make it a new habit.