I thought a little bit about this and I would say Apple Watch for me. When it first came out it was not perfect and there were lots of limitations to it but then Apple iterated on it with focus on Fitness based features and I finally ended up buying Series 5 version. I could definitely say the gamification (nudging you to close the rings and monthly challenges) has changed my habits and I am more active than ever before because of Apple Watch. It lived up to the hype for me!