Modern medicine’s come a long way in helping people with chronic illness manage and maintain happy, healthy, and long lives—with one main caveat. You have to take the pills your doctor prescribes, and that can be a whole lot harder than it sounds. 

Medication nonadherence is an estimated $300 billion dollar problem in the United States, and costs more than $100 billion a year in excess hospitalizations, according to nonprofit group Network for Excellence in Health Innovation (NEHI), which researches ways to improve health care. An estimated one-third of people never fill their prescriptions, and three out of four Americans do not take their medications as directed.