Memorial Day is for remembering those who have made the ultimate sacrifice.As Americans honor the day in their own ways, people across the country will be participating in a tough fitness challenge honoring fallen Navy SEAL Lt. Michael Murphy.The challenge, known as "the Murph," consists of a variety of strength training and cardio activities, which Murphy himself used to complete during SEAL training.AMERICANS SHOULD HONOR MEMORIAL DAY IN THIS WAY, MILITARY SERVICE MEMBERS SUGGESTMurphys former SEAL roommate, Kaj Larsen, told Fox News Digital how he also participated in these workouts, which have turned into a national movement of patriotism."Murph and I would often run to the pull-up bars and then do this workout where we did 100 pull-ups, 200 push-ups and 300 air squats, and then we'd run back to our barracks room," Larsen said."The total run was about a mile to the pull-up bars and a mile back, and this became one of Murphs favorite workouts."WHAT IS RUCKING? THIS POPULAR FITNESS TREND GOES BACK TO BASICS FOR BIG GAINSMurphy would often wear his body armor as a challenge, originally calling the workout "Body Armor."Now, tens of thousands of people on Memorial Day complete "the Murph.""Its a really beautiful way to honor him," Larsen said. "Murph would have loved the idea of thousands of people sacrificing through sweat. That was right up his alley."He added, "He loved working out. And I think he's smiling down on us as he sees us all doing one of his favorite workouts."The classic Murph consists of the following exercises, in order or broken up:Murphy and Larsen would often do the workout with a 20-pound weighted vest, which is optional.ARMY UNVEILS NEW FITNESS TEST WITH TOUGHER STANDARDS COULD YOU PASS IT?For those looking to attempt the Murph this Memorial Day, Larsen said there is "no one way" to do it.While some people train all year for the Murph, modifications are acceptable.This can include partitioning the reps of push-ups, pull-ups and squats into sets, or subbing out pull-ups for jumping pull-ups or assisted pull-ups with a band. The runs can also be walked, Larsen noted."The point is to do something hard that challenges yourself in recognition and honor of those who have made the ultimate sacrifice," he said. "And if you do that, you have done the Murph."Larsen, currently head of military investing and communications at Siebert.Valor, the military arm of Siebert Financial, spent 13 years in Naval Special Warfare as a SEAL and left the military at the rank of lieutenant commander.NYPD DETECTIVE SHARES GRUELING WORKOUTS TO MOTIVATE COPS TO GET IN SHAPEThe veteran spent his rookie years with Murphy, who joined through Basic Underwater Demolition SEAL Training (BUDS) in 2001.SEAL Officer Murphy, the son of a New York firefighter who is originally from Long Island, was part of a team that specialized in long distance and special reconnaissance.In 2005, during his first combat deployment to Afghanistan, Murphy was part of Operation Red Wings, designed to go after a senior-level Taliban operative, Larsen described.The operation has been memorialized as one of the greatest losses in Naval Special Warfare history.CLICK HERE TO SIGN UP FOR OUR HEALTH NEWSLETTERMurphys team was compromised, overwhelmed by superior forces as a firefight broke out. There were no survivors except for one SEAL, Marcus Luttrell.A Quick Reaction Force (QRF) helicopter with eight SEALs flew in to support the SEALs on the ground, Larsen said.This helicopter arrived due to Murphys moment of heroism, where he exposed himself to "excessive enemy fire" to reach radio communication, Larsen recalled."He got up on top of a boulder, which was the only place that he could make comms to call in the quick reaction force," he said. "This ended up saving the life of Marcus Luttrell."For more Health articles, visitwww.foxnews.com/health"Mike was killed on June 28, 2005, in Afghanistan. They identified him in part because underneath his uniform, he was wearing a New York Fire Department T-shirt FDNY T-Shirt as a tribute to his dad, Daniel Murphy."Murphy received the Medal of Honor for his actions that day, and the U.S. Navy commissioned a battleship named the USS Michael Murphy.Operation Red Wings has since been immortalized in a book by Marcus Luttrell and in the movie "Lone Survivor" starring Mark Wahlberg.A museum in Murphys honor was also built in his hometown of West Sayville, New York.Murphys workout was also picked up after his death by the CrossFit community, which turned it into a "massive cultural movement," Larsen said."The Murph is hard, and it's designed to be hard," he added."And I, for one, just appreciate everybody continuing to keep Murph and other soldiers like him who have paid the ultimate sacrifice in their hearts and in their minds."