The tag -- available in packs of three, eight or 15 -- simply sticks onto the clothes you wear most often. It's waterproof, so running it through the laundry is no problem, and its battery will last nearly two years. Just stick it on your gear and get on with your life. It measures all the usual metrics to provide personalized, real-time guidance for sleep and daily activity. For example, instead of simply telling you how many calories you burned at the gym, it'll tell you how much quicker you'll fall asleep as a result of that workout. And it monitors stress levels, thanks to respiratory sensors that measure breathing.

The tags are so discrete no-one will know you're wearing them, which is great for people looking to work on their fitness without fanfare. Of course, this could be a downside for the people who enjoy bringing up their metrics at every possible opportunity (you know who you are). Prices range from $99 for a three-pack to $299 for a 15-pack.