Oh. I've had problems with that (tight hips). What are the exercises?
Shoulder slides, should dislocations, and chins.
Should slides being where you keep your feet, butt, lower + upper back, head, arms and elbows pressed up against the wall and you raise your arms up above your head as if you're doing a barbell press without any of those areas coming off from the wall. And my lower back just absolutely can't even get close to staying pressed up against the wall, so I have to take a stance a bit away from the wall for my lower back to touch but it works.
The other is shoulder dislocations, where you take a resistance band or something long like a broomstick and and raise it over your head and behind your back. I can get it about 3/4 all the way but that's it.
Chins being where you just tuck your chin into your chest, those are pretty straight forward, don't have too much problem doing them.
What's annoying is that I went to a chiropractor over the summer for my externally rotated legs, duck foot essentially (caused mostly by tight hips too). He gave me some workouts for that which I do pretty much every day and it has helped a lot, but while there he couldn't have said 'by the way you have horrible posture?'