This is an easy range of motion activity to maintain your hip flexion. Lie on your back, and maintaining a neutral spine, draw one knee into chest. You may feel a stretch behind the hip or under the leg. If you feel a pinch or sharp pain within the hip joint, let the leg out a little so you do not feel this pain. Hold this stretch for 30-60 seconds on each side, 2-3 times per day.
If you have normal range of motion for hip flexion, you should be able to touch at least a portion of the thigh to the chest. If you are unable to do this, spend a few minutes doing this stretch each day. If you are unable to do this without pain, and it impacts your daily activity or sleep, you will want to get it checked out by a physician or physical therapist.