Plenty of companies these days offer their employees monetary incentives to exercise, lose weight or quit smoking. Join the program, take a physical, track your steps, your pounds, or your other vital stats, and usually, your employer will trim a healthy chunk out of your annual premiums — which, considering how much most workers are contributing to their health insurance coverage, ought to be a strong motivator. So why aren’t more of us getting healthier? Mitesh Patel, a professor of medicine at the University of Pennsylvania’s Perelman School of Medicine and a professor of health care management at Wharton, has been researching some fundamental questions about these programs. He joined the Knowledge at Wharton show on Wharton Business Radio on SiriusXM channel 111  to talk about when they work, when they don’t, and what incentives and structures are most likely to get us to adopt healthier habits.…