This is a really powerful stretch and very easy to do - all you need is a wall! So many of us spend too much time hunched forward over computers, phones, etc, and can benefit greatly from releasing tension in our chest and shoulder muscles. This is a great stretch for that!
Simply find a wall and stand with your side against it. Try to stand as close to the wall as you can. Reach the arm next to the wall back straight behind you with your palm on the wall, and your arm tracking back at shoulder height parallel to the floor. Press the arm against the wall as you try to bring your shoulders back in line with each other (imagine gently rotating the rest of your torso away from the wall) - you should feel a stretch across the front shoulder and outer chest muscles.
Hold this while taking deep and intentional breaths to settle into the position. Slowly release after about 20-30 seconds, and repeat on the other side. You can also add a bend of the neck away from the wall to include a neck stretch!