All chicks, male and female baby chickens, look more or less precisely the same. Yet the females grow into hens – able to lay eggs – while the males grow into roosters – no eggs, just lots of noise.

The brutal reality, then, is that breeders want to kill the roosters as young as possible, before wasting months of feed, space, and care on those unwanted birds.

Hence the chicken sexer: a professional able to divine the chicks’ genders at just a day old.

Apparently, however, chicken sexers can’t, by and large, explain how they know the gender. Instead, new chicken sexers learn their craft sitting at the side of an experienced sexer, watching the pro sort male and female, male and female, for months at a clip, until they, too, can reliably spot male or female themselves.

By now, after six years of owning CrossFit NYC, after having watched literally thousands of people learn perfect form on movements like the squat, pullup, and deadlift, I’ve begun to feel a bit like a chicken sexer of human movement.

I see someone come in the door of the gym, and even before they start working out, I can already tell that they have low back pain or shoulder pain, that they have tight hip flexors or calves, that they’re unable to squat to full depth or lock a weight out overhead.

And, of course, I notice it outside the gym, too. The difference is, if I tell one of our members at CrossFit NYC that they might want to stretch their external hip rotators, they’re usually grateful for the insight. Whereas, if I inadvertently blurt out as much to someone in my apartment building’s elevator, I get looks that put me on par with Silence of the Lambs‘ Buffalo Bill.

Still, I can’t help it. The vast majority of rotator cuff tears, blown ACLs, replaced hips – the movement injuries of modern life – could be easily avoided, with just a little time and attention spent on fixing imbalances and dysfuction before they spiral all the way to breakdown.

If any of you want to dork out, I’m happy to recommend a dozen great books on the topic. But, for most people, I now have a far simpler, faster recommendation:

The Mobility Workout of the Day.

The site’s about two months old, started when Kelly Starrett, a doctor of physical therapy in San Francisco (as well as an owner of San Francisco Crossfit, a national champion whitewater rafter and kayaker, and a generally smart and excellent guy) started shooting short videos of himself with his new iPhone.

The premise is simple: prescribing ten minutes or less of guided, high-impact stretching each day.

Whether you’re an athlete looking to maximize performance, or just a desk jockey looking to make it through the work day without your back freezing up, the Mobility WOD is a great place to start.

Besides, it’s only ten minutes. Certainly, not permanently jacking yourself up should be worth that kind of investment, no?

If you’re feeling saucy, I’d recommend starting from the beginning, with the first post, as you’ll learn a huge amount from each one, though you can also safely jump in at pretty much any point.

Stretch it out! Or don’t. But then don’t complain to me when everything hurts.