I bought an Apple Watch last fall in what I assumed was a silly, tech-geek pursuit of getting in shape. Surprisingly, the Activity app (the one with the rings) has completely transformed my body. I know all the tricks it's using to motivate me, but damn it, it works. I make sure to close my rings every single day and it shows: I've lost weight, gained noticeable muscle, and went down a notch in my belt. Oh, and I've heard it also tells time.