Maggie's Farm

Sedentary workers and sedentary people tend to develop a hunchback, a slouch, termed Postural Kyphosis. This is not really the same thing as Senile Kyphosis ("Dowager's Hump"), but it's in the same direction. Postural Kyphosis is reversible, Senile Kyphosis is not.

Back exercises are the best things for posture, generally. Dead lifts, especially. Not a bad idea to stick a post-it on your desk saying what your Mom said at the dining room table: "Sit up straight with your shoulders back." (She also always said "Stand up straight like a soldier.")

A few links on the topic:

5 Exercises To Fix Hunchback Posture From Office Work

You probably spend hours in front of a computer every day—so make sure you’re doing it right

Working Out Isn't Enough: Advice for Desk Workers

Desk Yoga to Improve Your Posture