At CrossFit gym in Greenville, they sweat during Memorial Day 'Murph' workout for Navy veteran

It starts with a one-mile run and ends with one too — sound doable enough? How about in between, try doing 100 pull-ups, 200 push-ups and 300 air squats, all while wearing a 20 lb. weight vest.

This is the "Murph" workout, practiced across CrossFit gyms on Memorial Day in honor of U.S. Navy Lieutenant Michael Murphy, who was killed in action in Afghanistan.

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Workout warriors packed the CrossFit Reaction gym in Greenville Monday to honor his memory through their sweat.

"Instead of just working out to get fit, you have in your mind that someone sacrificed their life so you can do whatever you want to do," said Christopher Payne, of Travelers Rest.

That provides an extra boost for this workout, which lasts up to four times longer than many CrossFit workouts.

It's particularly mentally challenging, said Jimmy Dotson, of Greenville, but he thinks about U.S. soldiers' sacrifice to help him power through.

"If they can sacrifice their lives for our country, we can sweat for an hour," he said.

It's a sign of respect to those fallen service men and women to do something hard on Memorial Day, he said.

There's real symbolism in that, more so than sitting on the lake and drinking a beer, said Chris Cain, of Greenville. 

"I think it's good to kind of get out and suffer a little bit," he said.

That suffering was bared together, as one gym.

"That's what the CrossFit community is," Dotson said. "You just come in and you do your work until it's done."

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