Cardio zone information is useful for those who are serious about their fitness, but not so much for the average sidewalk slogger. To make the feature more meaningful for the rest of us, Fitbit's added a Cardio Fitness Score component that lets you gauge your heart health against people of your age range and gender. Luckily for my ego, it turns out my resting heart rate is considered average to fair for women my age. Sorry to those of you who fall below average on this curve.

Steps are forgettable, but seeing my heart's performance right there actually spurs me to do something about my health. It's this type of personal info that will ultimately keep me wearing the Charge 2. But the new tracker isn't just there for your workout. It'll help you recover after. Fitbit implemented a new Guided Breathing mode that, like other stress-fighting wearables, will coach you through breathing exercises to help you wind down.

It's a well-intentioned feature that's quite poorly executed. You get the option of two- or five-minute sessions that you launch from your wrist. During these sessions, you'll have to look at the screen, inhaling when a circle expands, exhaling when it contracts. Throughout this, the Charge is measuring your pulse to tell how quickly and deeply you should be breathing.

Maybe I should be more fit than I am right now, but holding up my arm for two (not to mention five) whole minutes while trying to breathe in sync with the Charge was more strenuous than it should be. I couldn't comfortably see the circle unless I held the my wrist up in front of me, and the device had to be on me to detect my pulse. Fitbit could easily put this tool in the app to let audio guide you and still have the tracker send heart rate information to your phone.

Other Charge improvements include auto exercise recognition and multi-sport tracking to record more meaningful data for specific workouts such as running, biking and weights. The wearable can now tap your phone's GPS to show stats such as pace and distance in real time, as well as save a map of your route to the app. The Charge 2's battery lasted about three days on a half charge, which is similar to the Charge HR's touted five-day endurance. The new-gen tracker also maintains its sweat and rain resistance. A lot of the abovementioned features already exist in other trackers, however, so Fitbit isn't doing anything really groundbreaking.

Many of these tools -- such as auto exercise recognition and auto sleep tracking -- are also available in the Flex 2, which got quite a major redesign. Instead of looking like a smaller, thinner Charge with a horizontal row of LED lights at the top, the new Flex looks more like a Jawbone Up or Misfit Ray, with a more rounded, cylindrical tracker housed in a narrower band.