Typically, when doing a tummy tuck (abdominoplasty), your surgeon will try and make you as tight as is safely possible. This can lead to feeling like you will pull everything apart when you try and stand up. People typically walk a little hunched over to avoid this, plus it is usually more comfortable not to put tension on the incision. That said, walking hunched over isn't so comfortable either! I typically tell my patients to stand as upright as possible but to listen to their bodies; if it hurts or feels too tight to stand straight, then don't. Skin will stretch with time and usually by two weeks people are comfortable enough to be fully upright. Good luck!