Fitbit et al are well and good-- but gimmicks won't help get someone out of bed during our rainy season to get out and exercise. 
Fact is, exercise is work and until a person starts to feel and see the difference it makes, it's a hard path to get motivated and stay motivated. I don't know what a long-term study would show about extending commitment. 
This article reads a lot like one of those sneaky advertisements a writer recently complained about to the publisher. I seem to recall a recent article in another paper, also, about how Fitbit's status is severely being tested by other tech competitors. Hmmmmm…..