MSN: 5 Simple And Effective Shoulder Exercises To Relieve Stiffness And Increase Flexibility Naturally Shoulder stiffness is a common issue caused by poor posture, long hours of sitting, stress, or even sleeping in the wrong position. Over time, this tightness can lead to discomfort, limited range of ... 5 Simple And Effective Shoulder Exercises To Relieve Stiffness And Increase Flexibility Naturally