(CNN) -- Personal trainer Cornell McClellan was working out with President Obama one morning when he had a revelation.
"Being a personal trainer is just like being the president," McClellan told Obama, whom he has trained for 11 years.
That certainly got the president's attention.
"We're faced with similar things," McClellan said. "We have people that come to us, and they've created conditions or situations that maybe we've had nothing to do with, and immediately they want us to change it. Even if they don't do what they're supposed to, they're upset with us when it's not changed. So I thought our jobs were pretty similar."
McClellan spoke at last month's American Council on Exercise conference in San Diego, where he thanked fellow personal trainers who donated their time to help military families get fit.
McClellan splits his time between Chicago and Washington, where he helps the Obamas and key members of the administration stay in shape. The imposing former martial arts guru is one man in the world who can tell the president what to do -- at least when it comes to exercise.
"If we're short on time, we try to mix things up," he said. "We'll try to make sure there's some high-intensity stuff. We might do some weights, throw some cardio in there and throw some plyometrics in there with abs. We go from one thing he needs to another, because his time is short."
The president is in tiptop shape age 50. Obama passed a physical exam in October with a healthy body mass index and normal blood pressure and cholesterol levels. The doctor wrote that Obama was in "excellent health and 'fit for duty.' "
"I was very pleased," McClellan said. "We joked about it."
And McClellan is no doubt pleased with Michelle Obama's much-coveted arms, which are so admired that they have spawned exercise DVDs with titles like "Arms of a First Lady" and "Totally Toned Arms: Get Michelle Obama Arms in 21 Days."
Although it's easy to say that the presidential couple can get in shape easily because of their resources such as personal trainers and professional chefs, it's not just about that.
McClellan said busy people can realistically integrate fitness into their lives because it's a mental thing.
"He is the busiest man in the world," McClellan said of the president. "I don't have to prod him."
The excuses -- too busy, too little time -- just don't fly with McClellan.
Long before the White House, the Obamas made their health a priority.
Michelle Obama came to his Chicago gym 14 years ago, and her husband joined about three years later. Before she became first lady, she would go to McClellan's gym as early as 4:45 a.m.
It's about a mindset, McClellan said.
"People have to first understand the benefits," said McClellan, who serves on the President's Council on Fitness, Sports and Nutrition. By exercising and reaping its benefits on health and stress relief, he said, "it is how we can maintain these busy lives, and how we can sustain them."