Rounded shoulders and tight chest
Having rounded shoulders and a tight chest is a very common sign of poor posture and is prevalent amongst sedentary works. Spending excessive time in front of a computer can cause weakening and lengthening in the back muscles, and shortening and tightening in the pectorals. Rounded shoulders can also occur when the upper/mid back is neglected in the gym, and too much focus is placed on the chest muscles.
Neck and back pain
Poor posture causes muscle imbalances which in turn leads to pain. A forward head carriage, for example, can overwork the neck and upper back, as the muscles work to hold the head against gravity. This can eventually result in stiff joints and strain in the neck and upper back, causing pain.