>> What were the rewards like? I’ve seen those usually in the range of a
>> fraction of a percent of salary, which isn’t going to motivate anyone.
I worked in this space for a while (the company used Rails to do their apps!), so I'll give some input.
It varied from company to company, but most of our customers gave out tiered rewards. Everyone who participated got a step counter of some sort. Everyone who logged X amount of days recieved a t-shirt or water bottle. And the 'winning' teams would get wellness-related gift cards ($50-$250, again depending on the company). The cards were usually for sporting goods stores or 'healthy' items but sometimes they were for chain restaurants.
Now, when I say winning, there were often many teams that tied for first place. The reason was, for whatever activity you had to log (healthy foods, exercise minutes, steps), there was a daily cap. And we'd find obvious cheaters who would log all their activity on the last day of the program (or even for their whole team). People would call/email with support issues asking why they don't have the amount of points they should have, it's always a big ordeal. Teams accusing others of cheating...