Proper siting and standing posture is important to minimize imbalances in muscles in your trunk, legs, and hips.
When sitting for a long time, take breaks from poor posture by sitting up as straight as you can with your feet on the floor for up to 5 minutes every 1 hour. This can help condition your muscles to tolerate “good” sitting. Try a posture corrector (search online)
When standing for a long time, tighten you abdominal muscles and shift your weight from one leg to the other to avoid putting too much weight on one leg only.