HOUSTON -

Athletes going into the Olympic Games are at peak physical fitness, so you have to wonder: How do they get that way?

Several U.S. athletes have turned to the Navy SEALs for the ultimate workout and that same level of intensity is found right here in Houston. I decided to join the ranks.

Long before the sun rises, our group gathers in Memorial Park at 5 a.m. This is no gentle wake-up call.

It's SEAL Physical Training, 90 minutes a day, Monday through Friday. A full body workout led by veteran Navy SEAL and former Marine Jack Walston, who makes it clear he is "not a personal trainer."

We kick things off with an exercise called "chasing rabbits."

"We'll do it till we get it right!" Walston barks at us.

Then we're told to take a jog down to the "watering hole," where in a grassy area, we're told to lay flat on our backs as Walston hoses us down with icy water.

"Welcome to Day One, folks! Every day, it gets a little harder!" he shouts.

After being soaked down, he tells us, "Everybody on your feet!"

We head to a sand volleyball court to commando crawl all the way across. Then Walston orders us onto our backs: "Start backstroking to the other side. Ready, go!"

And that's just the first 15 minutes.

As we fall in line, we meet our comrades. While a few are entering the military, most are civilians: bankers, attorneys, even a neonatologist. The program has been around for 15 years in Houston and New York City.

"Anybody can do it if you're willing to do it. It's a lot of the mental approach. It's the mental toughness," Walston said.

After countless pushups, sit ups and sprints, every inch of your body aches. But you're pushed to keep up with your team and Walston said that's the key.

"We don't leave our teammates behind and we get to learn everybody's name which is something you don't normally do at your local gym," he said.

If you survive the two week boot camp, you're invited to become a lifer. Rosie Munive has been doing this for 13 years. When asked why she loves it, she answered, "It's the only thing that works."

Neonatologist Mari Afanador and her fiancé Brian Eaton are looking to get in shape for their September wedding.

Afanador hung in there on Day One. Eaton lost his breakfast.

"I thought it was very tough," he told me.

"You almost keeled over!" I replied.

"I actually did keel over, but it was fun," he said.

A friend inspired 56-year-old Ginger Boswell, a forest landowner and lecturer who drove in from Magnolia.

"I just really wanted to give it a try and look forward to completing the course," she said.

I asked her, "So you're going to be back?"

She smiled, "I will be back."

I barely hung in there.

At the end of the hour and a half, I asked Walston, "So I came out here first day, be honest, how did I do?"

He answered, "I thought you did a great job. You put out. You gave 110 percent. You didn't quit."

Two weeks later, we checked in on graduation day.

Only one student dropped out due to injury.

Afanador and Eaton said it brought them closer to each other and their teammates.

"Each day, you're stronger than the next and you just want to push past your limits," Afanador said.

After that one work out, I was sore for a week. I have a new respect for those who can hack it.