Alfie Kohn doesn't like incentives, and I often agree. One of his most recent essays critiques employers offering financial incentives to employees who adopt healthier lifestyle habits and behaviors. In short, he doesn't believe it will work.
His two primary objections are that (1) deeper psychological or sociological issues often are the true cause of these unhealthy habits, and (2) extrinsic motivation doesn't usually last in the long run. No argument from me on either front, but I do think #2 should be considered a constraint to address as opposed to a reason for not trying.
Let's say you offer a $50 reduction in monthly health premiums to individuals who quit smoking. Cash is the initial motivator, and it is indeed extrinsic. At some point, the monthly savings may no longer have its initial motivational appeal. So before the extrinsic incentive loses all its value, the wise employer would help individuals identify and connect with intrinsic motivators that may be surfacing as a result of no longer smoking: feeling better overall, able to engage in physical activities with family and friends, less labored breathing, etc.
So if you offer coupons to customers or discounts to members you need to understand the potential shelf life of the incentives. But with an intentional strategy you might be able to replace some of the initial attraction to save money with an internal awareness of other value being received.