On the inhale, reach high to the sky, and then as you exhale, reach forward with a long spine, allowing the upper back to round once you can't reach any further. If this is very challenging on your back or legs, give yourself a gentle bend in the back of your knees. You can also use a towel or yoga strap under your feet to get a fuller stretch.
Get to your best version of this pose and stay for five rounds of breath.