Jake Gyllenhaal's trainer hates fitness classes — sweating and getting sore doesn't equal a good workout

• Celebrity trainer and gym owner Jason Walsh hates the fitness industry.
• He told Insider he believes most people are in it to make money, not help others.

Jason Walsh is a gym owner and celebrity trainer who hates the fitness industry. In fact, he hates the word "fitness" and everything it stands for.

"I just despise the word 'fitness,'" Walsh told Insider. "To me, 'fitness' envelops everything I hate about the industry. 'Strength,' 'conditioning,' 'health,' and 'wellness,' those mean a lot more to me and have a lot more value. 'Fitness' to me is all the people who want to take advantage of the industry and make money."

Walsh started lifting weights around the age of nine, and, after graduating from the University of North Carolina, qualified as a strength and conditioning coach there. He began his career working with athletes before moving away from professional sport and into personal training in Los Angeles.

"Jessica Biel was one of my very first clients," Walsh told Insider. He has since worked with celebrities including Jake Gyllenhaal, Brie Larson, Matt Damon, and Bradley Cooper.

Walsh has now worked in fitness for 30 years and is the founder of Rise Nation, a workout studio offering VersaClimber classes, with clients including Jake Gyllenhaal, that has four US locations as well as branches in the Philippines and Australia.

"Rise Nation launched almost 10 years ago, and that was just a passion project," Walsh said. "I never wanted to get into boutique fitness."

Walsh's main gripe is that much of the fitness industry is designed to make money, not help people, he said.

"There's huge potential in the health and wellness industry right now, and unfortunately a lot of it is just a bunch of bullshit," Walsh said. "It's people trying to take advantage of people and make money."

Forget group classes — tailored workouts are key

Walsh opened Rise Nation because he was so "upset" with what was happening in many fitness studios, he said.

Walsh discourages people from attending most group workout classes as they can injure themselves if the workouts don't factor in people's individual bodies, injuries, and mobility, he said.

"It's a one-size-fits-all mentality in the industry and that kind of approach really gets people hurt," Walsh said.

Just sweating, raising your heart-rate, and making your body sore is not an effective way to train, he said. But he believes this is what many trainers and fitness instructors do because it makes people think they've had a good workout.

Ideally you should work with a personal trainer who will assess your movement and your body, and then tailor your workouts to build your strength and fitness while avoiding injury, Walsh said, and this is what he does with his clients.

Walsh trains his clients for resiliency and longevity, he said. "The fitness industry likes to use those to draw you in, take your money, but doesn't necessarily do anything for you," he said.

Stay away from overly complicated health and exercise advice

Walsh believes the fitness industry over-complicates things and people in it don't want the public to know that getting in shape and staying healthy is actually simple.

Sure, it takes dedication and consistency, but it's not that complicated, Walsh said.

"What I do is so fucking simple," Walsh said. "It's disgusting and it's boring."

But it's not necessarily easy.

"It's not magic," he said. "You've got to do the work. You've got to get uncomfortable and get used to being uncomfortable. You just keep doing it over and over and over and eventually there's progress."

Walsh used the example of how much stronger Brie Larson has become over her years training with him.

"Brie Larson, she was the girl who couldn't open a water bottle and then all of a sudden she's performing her own stunts and not getting hurt," he said.

Some aspects of the fitness industry aim to confuse people so they can keep selling diet and workout plans and products, he said.

"I just don't think there's any integrity in the fitness industry," Walsh said. "People are gullible and they're going to eat it up, but I'm just not going to be a part of that."