Could living a sedentary lifestyle cause shortness of breath? i dont exercise and i sit around most of the day, and sometimes it seems like im not breathing as deeply as i should be. is it possible for constipation to affect breathing?

A sedentary life style does not cause shortness of breath. I will however lead to being de-conditioned or out of shape. If this SOB is new, being sedentary can lead to forming blood clots which can lead to a condition call pulmonay embolism. In you description of needing to take a deep breath, this occurs with anxiety. And lastly, no constipation does not affect breathing. See your PCP to sort it