How to Do the 12-3-30 Workout and Customize It for Your Fitness Level

HIIT, Metcon and now 12-3-30. It seems like there's no shortage of cryptic workout names out there. And if you're curious to learn more about the treadmill workout routine that's sweeping social media, you're in the right place.

Learn how to do the 12-3-30 workout on a treadmill near you and how to customize this routine for your fitness level.

The 12-3-30 workout was originally created by Lauren Giraldo, who posted it on her YouTube channel in 2019. Since then, the workout has gained a ton of popularity on social media, namely TikTok.

"I do this every single day — or at least I try to do it every single day — and it's really easy for me because it's just going [to the gym] and doing this one thing," Giraldo says in her original YouTube video. "Before, I used to get very overwhelmed when I'd walk into a gym because I wouldn't really know what to do ... This [workout] made it really easy for me to do the same thing every day."

The workout is pretty straightforward: You treadmill walk at an incline of 12 at 3 miles per hour for 30 minutes, according to Carolina Araujo, CPT, a California-based certified personal trainer and strength coach.

Although this walking workout isn't too complicated, it offers more benefits than you may think. After all, walking at a high incline is no walk in the park (pun intended).

"I like this routine because it's great for building your cardiovascular health, and you get some strength benefits with the high incline," Araujo says.

Walking on an incline activates your calves, glutes and hamstrings more than strolling on flat ground, according to the Iowa Heart Center. And the effort bumps your heart rate higher, helping improve your overall stamina and total calorie burn.

It may be called the 12-3-30 workout, but you can (and should) manipulate the incline to fit your fitness level, Araujo says. The easiest way to modify this routine is by reducing the incline.

For those who don't incline walk too often, level 12 can feel pretty steep. Instead, Araujo recommends first timers start at level 6 or 7. Generally, this incline feels more doable for the full 30 minutes, but you can definitely bring it down more if needed.

You don't have to do level 12 at 3 miles per hour for the entire 30-minute workout, according to Araujo. Breaking the time into chunks of walking intervals is a simple way to make it easier — or harder.

For those who need to modify the workout, do one minute at level 12 at 3 miles per hour, and then do two or three minutes at level 5 at 2.5 miles per hour. Then, alternate between these two levels until you hit 30 minutes.

If you want an added challenge, you can increase the speed, she says. The incline is already pretty high, so keep that where it's at. But you can bump the speed to 4 miles per hour for one minute and then bring it back down to 3 miles per hour for two or three minutes.

"Don't get too attached to the numbers," Araujo says. "There's no rule that says you ‌have‌ to do this workout for 30 minutes, especially if that doesn't feel manageable for you."

Ideally, you should aim to get about 150 minutes (or 2 1/2 hours) of moderate cardio activity each week, according to the Centers for Disease Control and Prevention. While this amounts to about 30 minutes of activity, 5 days per week, you can cut down the total time per session and walk on more days instead.