The chair is a very stiff place to be. Even with perfect posture the body eventually loses range of motion, conforming to the chair. Take 3-minutes to stand, move, and change position. Practice easy exercises and movements that take the body through a wide range of motion. Try sitting cross-legged or sit in deep squat position. Practice stretches that feel good, paying special attention to areas know to be tight of limited in range. These breaks can help fight muscle fatigue as well as stiffness or joint pain.