You may as well ask if I’ve eaten as ask if I’ve exercised. I work out every day. Some days more than others. I can’t imagine life without it.

I don’t need encouragement, prompts, or prods. If I had my druthers, I’d spend my day in athletic gear playing.

So the “quantified self” movement—which mainly centers on fitness, though some aspects relate to general wellness including sleep and moods—intrigues me in the way it would tempt any athletic nerdy type. When I enter stores that sell these devices, I fondle the packages and read all the various options. I try to decide which one would best fit into my lifestyle.

But I haven’t bought one—and I won’t.

First, their ridiculous inaccuracy bothers me. Sure, if you need a general notion of whether you’ve gotten more or less activity than the day or week prior, primarily with an eye to increasing or maintaining your exercise levels, then activity tracking devices make sense. I don’t need the reminder. If I bought such a contraption, I’d want it to give me highly precise data to improve my workouts. These don’t.

Further, I obsess enough already. I obsess about what I eat, when and at what exertion level I exercise, how I structure my time, each item I add to my to-do list, what goes on my calendar, and whether my activities align with my goals. As it stands, I’ve had to place limits on exercising, rather than the opposite. I don’t need a device to make me obsess more.

And about my goals: The ease of hitting my exercise targets tempts me to overdo workouts at the expense of other objectives. Last year, I began to track each workout in a spreadsheet that detailed length, level, distance (for running), and how it felt. The intense focus on minutes and seconds and how I’d fueled to achieve my results had me exercising up to and above two hours a day. I had to stop. With exercise, as with everything, returns diminish after a certain threshold. And in the meantime, I’d let my other goals languish.

Have you bought into the quantified-self movement? Why?