That cool, stylish girl you always see at the studio may be wearing an outfit that looks effortless, but don’t be fooled—just like the messy half-bun, it takes serious styling know-how to build that “I threw this on” look.

A tell-tale sign of someone who has the nonchalant aesthetic down to a tee? The knotted tank.

It’s a simple style trick, but it does wonders to upgrade your look from athleisure novice to full-blown cross-training trendspotter. Even better, it can be achieved in the same amount of time it takes to slip on your barre socks.

“I love knotting my tank while I work out,” says Melissa Eckman, the fitness and fashion Instagrammer behind Yogspiration. “It’s stylish, but it also helps me see my form much better since the excess fabric doesn’t get in the way.”

If you’re looking to tie the knot yourself—and have had less than stellar success—Eckman says there are some secrets to pulling off the look flawlessly every time.

Pro tip: “The shirt will stretch once it’s tied, so get it as tight as you can before you knot it.”

“The shirt will stretch once it’s tied, so to make the perfect fit you have to get the shirt as tight as you can in the beginning,” she says. “Then, you wrap the fabric around your finger and pull the end through to tighten.”

Once you’ve got the basic technique down, Eckman adds, there are lots of variations to play with. If you’re going to be on your feet for an entire sweat sesh, knot in the back to create a crop top or front-and-center for a slimming look. And if you’re doing Pilates, yoga, or anything else where you’ll be spending time on your back or stomach, tie your top on the side for a slouchy and relaxed vibe that won’t get in the way of your workout.

When in doubt? Utilize that extra hair band to keep things cinched (there’s a reason why you’ve kept an emergency stash in your gym bag)—or just opt for a pre-knotted tank option.

Now that your tanks are fashionable and functional, put them to the fitness test. Try these three model-approved moves to get you ready for any and all crop tops, or fire up your core with this ab-tastic, equipment-free workout from SoulCycle star Akin Akman.

This story was originally published on December 7, 2016; it was updated on July 12, 2018.