Gunnar Peterson is no stranger to helping people get in tip-top shape. The trainer's client list ranges from the Kardashians and Sofia Vergara to Tom Brady and Mike Tyson, so it's safe to say he knows a thing or two about fitness.

Peterson is the Chief of Athletics at F45, a functional training gym with locations all over the world. “F45 is a comprehensive, functional exercise program," Peterson tells Parade. "Don’t think of it as a workout—think of it as a program.” Rubber Bands Recyclable

As Peterson explains it, F45 is more than a cycling or running class. "We program strength, cardio, hybrid; we program in phases throughout the year so there are ways to regress and progress everything as you go along. It’s not a class where you chug along and then do a big sprint at the end … there's nothing wrong with those types of classes—we just get more into the shades of gray."

Perhaps most important of all, Peterson emphasizes that F45 is all about making it easier for you to move around in your day-to-day life. “With F45 you’re more ready to deal with what life throws at you, whether it’s reaching for your seatbelt, putting your bag in the overhead bin, picking up your kid and putting them in their crib, or grabbing a kid who’s sprinting into the street. F45 sets you up for more success in the real world.”

Read on for more of Peterson's top fitness tips.

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While Peterson says he would typically never prescribe just one workout move (he is a trainer, after all), if he was going to, it would be a squat with a twisting press, which is meant to be done with dumbells. "You’ll get upper body, you’ll get lower body, and if you do enough reps, you’re going to feel a cardiovascular demand."

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In terms of how many reps you should do, he says that varies from person to person. "If I’m talking to my dad who’s 85, I’d say, 'Do [half a set], Dad.' If I’m talking to someone who works out all the time, I would tell them to do three sets of 10.”

Peterson has worked with every fitness and recovery tool under the sun, and he says his absolute favorite cardio tool is the Inertia Wave. "The Inertia Wave is tubing that’s about nine feet long. Think battle ropes, but made out of very strong rubber bands," he says. "They pull you forward, and you have to resist that pull. When you move them like ropes, from an elastic standpoint they expand and contract. They’re very dynamic, and you can get ridiculous cardio with them. They’re easy to travel with and relatively inexpensive, too," he says.

From a strength standpoint, Peterson is all about adjustable dumbells.

And recovery-wise, Peterson loves the Theragun massage gun. "It's a terrific tool, and pretty versatile," he says.

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If you're reading this thinking, This all sounds great, but I don't even know what an adjustable dumbbell is, worry not. Peterson says that if you're new to working out, or haven't worked out in a while, the very best thing you can do is just start. 

"Don’t overthink it. Just get started," he says. "People. say 'Oh, I’ll start on Monday, or I’ll start after my 30th birthday.' No, start today. If you’re talking to me before noon, start today. If you’re talking to me after 3 p.m., start tomorrow."

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As for what to do, Peterson suggests taking an F45 class since it will be fun and engaging, and there's a trainer there. But if you don't love group fitness, go to the gym with a friend who likes working out and is patient and follow along with them—but just do about 50% of what they're doing. "And if you have the means, hire a trainer," Peterson says. "A lot of people think just because they have two arms, two legs and a torso, they can work out. And you can, but you can also get injured easily.”

Ever avoided lifting weights because you didn't want to "bulk up?" According to Gunnar, that's one of the biggest fitness misconceptions out there. Actually, lifting weights will only tone you up and make you healthier. "The fact that lifting weights will make you big … that's not how it works. Eating more calories than what you are burning on a regular basis is what makes you bigger."

So go ahead, lift those weights—as long as you're keeping your diet healthy, you can expect a toned, lean look.

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