The expansion isn't coming out of nowhere. Roughly half of everyone who got an Apple Watch in the more limited program was active enough to avoid paying more, Senior VP Brooks Tingle told CNBC. And when there was a 20 percent increase in activity with the program, it only made sense to widen its reach to every customer. And if you're an Android user or just don't care about having a full-fledged smartwatch, you can get a free Fitbit device instead.

There are certainly concerns about programs like this. Your insurer isn't really tracking your every move, but you're still sharing some of your health data in order to get a discount. Also, there are worries that this hurts anyone who doesn't have the time, money or basic ability to work out. John Hancock says it's transparent about the possibility of paying, but that could still mean a rude surprise if you're injured or become a mother during the 2-year period. This is mainly about reducing health problems for people who are relatively well-off and don't anticipate any upheavals in their lives.