Hip Flexor Lunge
On the front of your hips you have the hip flexors, which are slack as we sit. The days, weeks, and years spent in that near-constant hip flexion cause these muscles to adaptively shorten, which can cause imbalances all over our body. Simanksy says this lunge is one of the best ways to stretch them.
Try it: Stand with your back to a wall, about two feet away. Sink into a lunge so that your front knee is at a 90-degree angle, and your back leg is bent, knee on the floor and foot up and against the wall. Pull your shoulders back and drive your hips forward to feel a deep stretch in the hip flexors; hold this for 30 seconds, relax for a few seconds, then repeat. Continue for 2 minutes, and switch sides.