What is the 12-3-30 workout? Experts explain the internet’s favorite new fitness routine

The 12-3-30 workout was made famous by social media star Lauren Giraldo

woman walking on treadmill and lauren giraldo on template
(Image credit: Future/Getty Images)

The 12-3-30 workout by Lauren Giraldo is actually much simpler than its name might suggest and can be highly effective for weight loss. Social media star Lauren became a fitness sensation after sharing this 30-minute treadmill routine online—and it couldn't be easier to recreate at home or at the gym. 

The key principle of the 12-3-30 fitness routine—which originally appeared on TikTok—is swapping treadmill running for incline walking for weight loss. All you need to get started is access to a treadmill and a good pair of trainers (see our guide to best running shoes for top trainer recommendations). 

Lauren Giraldo rose to fame as an actress in her teens, but the vlogger really started making waves in the fitness world after sharing exercise videos online. The star's 12-3-30 TikTok video was a viral hit, shared by more than 2.7 million people, with followers raving about the results. Talking about the workout online, Lauren says, "I used to be so intimidated by the gym, and it wasn’t motivating. But now I go and do this one thing, and I can feel good about myself." 

So, is the 12-3-30 workout really worth all the hype and why is it so effective? We asked the experts about the benefits of the 12-3-30 workout and how to get the most out of it. 

What is the 12-3-30 workout?

The 12-3-30 workout by Lauren Giraldo is a very simple concept. Lace up your trainers, hop on a treadmill, adjust your gradient/incline and speed, while setting a timer for 30 minutes on your fitness tracker or the treadmill machine. 

You'll then walk for 30 minutes at the same incline and speed. During that time you can listen to your favorite podcast, watch a Netflix show or tune into an audiobook as your stroll. 

To do the Lauren Giraldo treadmill workout you should: 

  1. Warm-up with a brisk walk for five minutes 
  2. Turn the gradient on the treadmill to 12% 
  3. Turn the speed to 3 mph (4.8km)
  4. Walk for 30 minutes
  5. Cool down with five minutes walking on the treadmill at 0% gradient 

Unlike HIIT treadmill workouts, there are no intervals or changes of pace. All you need is a treadmill and half an hour to work out. Three miles per hour is an average walking pace on a flat surface, so is an achievable goal. Although, of course, it all depends on what level of fitness you start with. Lauren herself gradually worked up to a full 30 minutes, but in the beginning, she took frequent breaks.

Watch how to do Lauren's treadmill workout: 

How to start the Lauren Giraldo treadmill workout

If you're new to treadmill workouts and find the gradient or speed daunting, adjust the intensity to get started. "Adapt the gradients and paces for your level and consider breaking the 30 minutes up into intervals with short rests, and building up to 30 minutes over four to six weeks if you're a total beginner,” suggests athletics coach Tom Craggs. 

Walking coach and author of Walk off Weight, Michele Stanton, adds, "Your muscles work harder as you increase the incline, so starting at a high incline without acclimating your body could leave you feeling sore or even injured. A high incline stretches the calf which tends to be tight for a lot of people."

To get started, you could reduce the incline to 3% or 4% and challenge yourself to hold the pace for as long as possible. Then, when you feel ready to do so, build up your time and gradient as you get fitter and stronger. The speed at which you progress will be different for everyone, so don’t compare yourself—work at the level that’s right for you. It should feel challenging, but not so much so that you don’t want to do it again. 

It's also important to maintain good form as you walk. Engage your core, keep your shoulders back and your head up. Always look straight ahead, rather than down at your feet on the treadmill. 

What are the benefits of the 12-3-30 workout?

It builds fitness and stamina

It is certainly a good workout for building fitness. "The treadmill isn't all about running. Power walking on the flat or even hills can provide a great workout, often with less impact on joints than running," says Tom. 

"A 30-minute walk with a high gradient such as 12% working at a strong steady intensity will certainly get your heart rate up, be a test for your posture and core muscles and means you will have to engage and drive with your glute muscles to maintain your position on the treadmill belt," he adds. 

It aids weight loss

For those turning to walking for weight loss, the 12-3-30 workout will help you mix up your usual walking routine and you'll burn more calories than if you were walking on a flat surface. But remember, any weight loss program should combine exercise and healthy eating, including some of the best (and most nutritious) foods for weight loss, for healthy and sustainable results. 

It helps shred belly fat

If you are researching how to lose belly fat, Lauren Giraldo's treadmill workout is a great exercise option. By doing the 12-3-30 workout three times a week, you can really improve your cardiovascular fitness, burn calories and work your core and glutes, too. Walking uphill also has a strength training element that will help to build muscle. You will also use your back muscles more than you might expect, which can help build strength in this often-neglected area. Though, for the same reason, anyone who suffers from upper and lower back pain should be careful when walking at this incline continuously for 30 minutes. 

It improves heart health

Experts credit aerobic exercise to helping to keep your heart healthy. It will not only lower your blood pressure and heart rate, reducing your risk of heart disease—but, it will also pump bloody more efficiently around the body.

The 12-3-30 workout is a great aerobic exercise, it will get your breathing and heart rate up as you walk at a brisk pace on the incline. But, will also be kind to joints because of its low impact nature. 

Why the 12-3-30 method is great for women over 40

Lauren Giraldo is only in her 20s, but the 12-3-30 workout is also a must-try for those aged 40+ who are embarking on a new journey into fitness. 

In the walking vs running debate, we're often reminded that running can be tough on joints. As you age, you naturally lose bone density, but by doing the 12-3-30 workout and strengthening your muscles and bones you can combat this natural loss and reduce the risk of osteoporosis without putting pressure on joints in the way that running does. 

If you're returning to exercise after some time away, it's a great workout for building up your fitness levels again. You can reduce the gradient and pace to take things at a speed that feels comfortable for you before taking it up a notch as you progress. 

If you aren't a fan of other cardio-based workouts, such as running or spinning, walking on a treadmill at an incline is a great way to get your heart rate up and improve your cardiovascular health. 

12-3-30 verdict—is it worth the hype? 

Walking is always great for your health overall, and by doing the 12-3-30 workout and adding an incline you'll activate lots of other muscles in your body, including your core and arms. 

And although it may be an average walking pace on flat ground, with that incline it will certainly get your heart rate up and you’ll break out into a sweat. However, a good exercise program should involve variety, and using the same muscles every day in the same workout will increase your risk of injury. If you really enjoy the 12-3-30, it’s still a good idea to limit it to two or three times per week and mix it up with strength training and other forms of cardio such as spinning classes, HIIT workouts or the elliptical machine.

As Michele points out, “When you're pushing yourself, your posture may suffer, especially if your core isn't strong, which can lead to back pain. You'll get better results from exercise if you do it consistently, so building up gradually is a better approach to building an exercise habit and getting the results you desire.”

Whatever your health and fitness goals, when it comes to trying a new workout like the 12-3-30 routine, the most important thing is finding something that you enjoy and that works for you. Choosing an activity you actually like doing is key to helping you stick to a program and keep workout motivation levels high. 

w&h thanks athletics coach Tom Craggs and Walking coach and author of Walk off Weight, Michele Stanton for their time and expertise. 

Kate Carter
Kate Carter

Kate Carter is an experienced journalist who worked for the Guardian for a decade before going freelance. She writes for the Guardian, Runners World, and World Athletics amongst many other publications, and presents for The Running Channel. She is also a sub three hour marathon runner and an England Athletics coach.