It was 2005 and I was attached at the hip to a cellphone—literally, thanks to a swivel holster. This wasn't just any cellphone: It was a BlackBerry 7250, one of the first to free us from our desks and put email in our pockets.

Every few years I replaced it with a new model. I was hooked on the physical keyboards and how fast I could respond to messages. I clung to BlackBerry as long as I could, but then, one winter day in 2010, I just broke it off.

...