This is a great stretch for midback pain and tightness.
Perform 3 sets of 20 reps, 2 times per day.
Begin on all 4’s with your hands under your shoulders and your knees under your hips. Extend your back upward into a “mad cat” position.
Next, flex your back downward to sag into a "cow” position, really let your belly hang. Slowly transition back and forth between these two positions.
Repeat in a slow coordinated movement as directed.