It's no secret that our posture falls apart whenever we sit for an extended period of time. We slouch forward, lengthening the muscles of our upper back and tightening our chests. One exercise to combat these postural deficiencies is the shoulder blade retraction. Grip the steering wheel with both arms without bending at the elbows. Pull your chest toward the steering wheel while driving your shoulder blades together, tightening the muscles between them. Hold the position for one or two seconds, then release. That's one repetition. Assuming you have the time, perform two to three sets of 10 repetitions. "The time under tension is really important," says David Peterson, gym owner and personal trainer at Infinity Fitness in Darien, Conn. "Feeling yourself squeeze the shoulder blades together is much more important than just moving yourself forward or backward" [source: Peterson].
You can also try the inverse exercise: shoulder blade protractions. Keep your arms straight and round your back as you push yourself away from the steering wheel. This works the serratus anterior muscles running along the side of the body near the ribs.