Do you need to worry about back pain? When you are young and your joints are strong, poor posture usually doesn’t cause back pain or limit mobility. As you get older, however, if poor posture goes uncorrected, you begin to feel the effects on your joints. It will become more difficult to sit for long periods or to stand up from a sitting position. You may gradually lose some of the flexibility in your joints and start to feel pain in your joints. The effects of poor posture continue to worsen with time.