Major: Respiratory Therapy
You can live without water for a few days and without food for a few weeks. Without air, though, you'll suffer brain damage within a few minutes and die after about ten minutes. Breathing, then, would be a pretty good thing about which to become an expert.
The practice of respiratory care requires comprehensive knowledge of many technical and physiological concepts. Among a ton of other things, Respiratory Therapy programs will teach you about the therapeutic use of medical gases, oxygen-administering apparatuses, drugs and medications, ventilatory control, pulmonary rehabilitation, and home care.
As a respiratory therapist, what you'll probably do when you get out into the real world is treat people with breathing disorders (and, by the way, you shouldn't have any trouble finding a job). Respiratory therapists work in hospitals and intensive care units with (often critically ill) patients who have asthma, cystic fibrosis, emphysema, and AIDS. They provide life-support for premature infants; perform cardiopulmonary resuscitation and maintain life-support systems; and assist physicians with bronchoscopies, arterial cannula insertions, and heart catheterizations. In a nutshell, they save and perpetuate human lives on a daily basis.