Gunnar Peterson on Building Your Sustainable Fitness Routine

Trying to go from zero to 100 in your fitness game? According to celebrity trainer Gunnar Peterson, the founder of the Common Ground training app, the key to fitness success isn’t going hard overnight—it’s building success gradually. 

In fact, the quick fix mentality might be harming you more than helping you, he explains: “Ease into it. If it’s too much, too soon, it’ll fail.”

Peterson, who has trained pro athletes to A-listers like Angelina Jolie, Matthew McConaughey, Mike Tyson, Dwayne “The Rock” Johnson, Arnold Schwarzenegger, and Sylvester Stallone, believes in keeping it simple: show up, work smart, and don’t BS yourself. Khloé Kardashian has known Peterson since she was 14 years old—he has trained her entire family. 

Time, energy, and money all go into a workout, which is why Peterson says it’s important to make exercise fun. On Khloé In Wonder Land, Kardashian and Peterson sit down to talk about making fitness a sustainable part of your lifestyle and his approach for adding value to any workout routine. The legendary trainer also debunks fitness misconceptions and shares how to take health and wellness beyond the gym.

From production assistant to fitness 

Peterson’s journey didn’t start in a gym. As a self-described “fat kid,” he was enrolled in Weight Watchers at age 10, but his life changed when he discovered how fitness and nutrition work together. Gaining control over his weight became a powerful motivator and he wanted to share it with others. 

After a short stint as a production assistant, Peterson started training clients as a side hustle. When he realized he was earning more as a part-time trainer than at his day job, he made the switch to full-time training. Twenty years later (including a three-year stint as the Lakers’ head strength and conditioning trainer), he’s one of the industry’s most respected voices.    

While many trainers focus on specific workout plans, Peterson emphasizes that what you’re really selling is “energy and an experience.” “Your energy either attracts or repels people. If your energy speaks to your workout, people will want to come. I worked out this morning, and I was giddy. Your exercise programs should do that. People are coming for the energy,” he says.

As someone who struggled with her weight and body image when she was younger, Kardashian says she found solace in Peterson’s early morning training sessions after her divorce, describing them as her “safe haven.”

Find what you’ll actually do

The fitness industry often glorifies suffering with mantras like “no pain, no gain.” But if you really want to see long-term results and maintain your fitness, the trick is sustainability. 

“Why would you buy a treadmill if you hate running? What do you like doing—bike, rower, climber? If it’s sustainable, it’s successful. If it’s not sustainable, it’s going to fail,” Peterson says. 

This philosophy extends to working with clients. Peterson prepares meticulously for each session but expects reciprocal effort.  “I can’t come at this at 110 percent energy, and I prep the workouts the night before, and you come in not wanting to do it. I’m not selling fitness to anybody.”

Make movement non-negotiable

If you think you don’t have time for exercise, think again. Peterson is methodical with his workouts: “How do you fit it in your schedule? You have to make time for it because if you go down, you need time to recover. You’re going to be in a hospital or dead.” 

His advice? Just begin. “Start with a 30-minute walk, then another, and build from there,” he says.

While many fitness influencers and aficionados are big on balance, Peterson is not a fan of the word “balance.” “I don’t think you have balance. You go hard and get obsessed with everything. You can’t have balance if you have a new project or new fitness goal,” he explains.