You'll see them marching ostentatiously on the stop while they wait for the office kettle to boil, or trotting up and down the train platform in the morning, as if an extra 45 seconds of movement a day is going to starve off heart disease.
These people have managed to convince themselves that their friends care how many steps they have taken or what their heart rate is. For the avoidance of doubt, literally no-one does.
But what's worse than a FitBit bore who wears their tracker to the gym? A FitBit bore who wears it during sex.
Yes. Really.
One such bore is renowned cricketer Andrew "Freddie" Flintoff, who admitted this week that he likes to wear his Fitbit in bed because it "makes him try harder."
Oh Freddie. Poor, sweet Freddie. And more importantly, poor Freddie's wife, Rachael, who made it very clear that she hates the FiBit, saying:
"Things are happening and then your husband's wrist is flashing telling him his heartbeat and how hard he's working. It's really wrong. It's putting me off though. It's like you're seeing it as another training session rather than anything else. It's really not nice."
It would be admirable that Freddie wants to "try harder" during sex, if it was in the hope of making sex a more pleasurable experience. Sadly when it comes to sex, trying harder does not mean doing it harder.
More aggressive thrusting does not, nine times out of 10, equate to better sex. In fact it often leads to much worse sex and I've never met a woman whose idea of a good time is a man climbing on top of her and ploughing away until his wrist starts buzzing.
Who's he satisfying, you or his FitBit? Of course it's admirable to want to become a better lover if the intention is to give more pleasure to the person you are in bed with. But the FitBit is a distraction from that goal.
It turns your sexual partner's body into a training ground and makes sex into a competition - one that you are having with yourself and really doesn't have a winner in the end. It's not just men who are guilty of this.
Women's magazines have been publishing cutesy breakdowns of how many calories you burn in a sex session, by position, for decades. If you want to burn calories, go take a HIIT class. If you want sexual gratification, go to bed.
Please don't try and amalgamate to the two.
I can attest that when I've slept with athletic men, there has been a real tendency to see sex as a work-out, and a demonstration of virility and strength. An ego trip, of sorts. Making you orgasm isn't about giving you pleasure, it's about winning.
If you're audibly raising the rafters he'll be pleased, but not because you've enjoyed yourself but because it's a tangible proof of his achievement.
Being good in bed is making sure that the other person enjoys themselves. It means ensuring that their pleasure is real and abundant, and that that they feel exhilarated and satiated afterwards.
So please, guys everywhere, leave the FitBit on the bedside table until you're finished, because none of those are things can be measured by a wrist watch.
