Someone gave me a Jawbone (competitor to Fitbit) as a gift. I refuse to use it, because it an functionally opaque piece of garbage that requires that I sign up for an online service. This nearly always means that someone plans to sell my data.
These punk-ass little toys would not survive my principal physical activity, which requires seawater immersion tolerance to at least 3 meters, and occasional water impacts at upwards of 40km/hr. The other is yoga, and I am not wearing any encumbrances during that.
I also detest wearing anything on my wrists or arms. I wear a wristwatch only during travel, or if I have an appointment, or occasionally if I need to gauge time to renew sunblock. Two of my wristwatches, ripped away by impacts, are now somewhere on the bottom of San Francisco Bay or inside some bottom-feeder.
Speaking of bottom-feeders, I have something for you, Mr. Tech CEO. The only "tracking" that I support is the tying people who propose it, onto active railroad tracks.