Affix a resistance band around a solid rack or pole.
Move away until the band gives you some resistance.
Pushup from a pushup postion and bring your foot up level with your hands.
The band should be halfway up your inside leg, with you turned side on to where the band is fixed.
Make sure the band is pulled tight to provide you with some resistance and move around in this position until you feel a stretch.
Feel free to move around in this position, you can push your knee wider with your elbow or move up into more of a lunge.
See what suits you best.