Parting with your own money is painful. But it is effective.

That’s also a lesson in Volpp-led research on getting people to lose weight and exercise more. One recent study gave incentives to patients by entering them into lotteries or into deposit contracts for meeting weight loss goals. Those in the lottery group were eligible for a daily lottery prize with frequent small payouts and occasional large rewards — but only if they clocked in at or below their weight loss goal. People in the deposit group invested their own money (generally a few dollars a day), which was then matched by researchers. They’d get their money back — and then some — if they met their goal at the end of the month.

At four months, both incentive groups had lost more than three times as much weight as the control group (about 14 pounds versus four pounds), but the deposit group lost slightly more than the lottery group. A similar study found that patients were more likely to walk 7,000 steps a day if they were given an upfront payment — part of which had to be returned each day that they didn’t meet their exercise goal — compared with lotteries, rewards or old-fashioned encouragement.

Other work has highlighted the power of defaults — which in health care can have life-or-death consequences. And perhaps nowhere is doctors’ default tendency more apparent than in our bias toward aggressive end-of-life care that favors quantity over quality of life.

With this in mind, researchers studied whether the type of end-of-life care patients choose is influenced by how we present the options. Terminally ill patients were randomly assigned to complete one of three advance directives: The first group received a form with the comfort-oriented approach preselected; the second had the aggressive care box checked; the third had both options left blank. Patients were free to override the default and select any option they preferred.

Nearly 80 percent of patients in the comfort default group chose comfort, while only 43 percent in the aggressive care default group did. (Sixty-one percent of patients without an embedded default opted for comfort.) It seems, then, that even critically important decisions about how we want to live our final days are affected by what comes pre-ordered on the menu we’re given.