Once thought of as a training routine reserved for soccer moms and granola-crunching free spirits, yoga offers athletic benefits that can no longer be ignored. Elite athletes are embracing yoga in a big way, and they’re discovering that some of their long-held beliefs about the practice are dead wrong. One of the most common misconceptions? Yoga is easy.

Many athletes see un-weighted yoga poses and instantly conclude they’re not challenging—especially compared to their punishing weight room routines. But once they finally give yoga a try, they realize they couldn’t have been more wrong.

Here are some eye-opening comments about how difficult yoga truly is—even for the best athletes in the world.

Eddie George, Former NFL Running Back

Entering the NFL after a tremendously successful college career at Ohio State, Eddie George was looking for a way to get an edge. He dominated the weight room and ran like the wind, but he was looking for something to improve his flexibility and durability. That led him to yoga. It didn’t take long for George to realize that massive numbers in the weight room don’t equate to yoga success. “When I first got into a Down Dog, I couldn’t hold myself there for more than 10 seconds,” George told STACK. “Here I was benching 400 pounds and squatting 500 pounds, but I couldn’t even support my own body weight for more than 10 seconds … It made me think, ‘This is something I want to get good at.’”

RELATED: Eddie George’s Beastly Yoga Workout

Nate Burleson, Former NFL Receiver

Nate Burleson recently retired from the NFL after spending time with the Seattle Seahawks and Detroit Lions. While with Detroit, he got turned on to yoga. Thinking it would be a breeze, he decided to give it a shot. “I remember when somebody first told me to do yoga. The  first thing I thought—‘that’s for girls,’” Burleson told CBS Detroit. “I had no idea how tough it was.” Burleson quickly realized that big muscles and a fast 40 don’t make you a yoga master. “There’s these old ladies in [the class], and they’re looking at me like, ‘You call yourself an athlete?’”

Ken Lucas, Former NFL Cornerback

Ken Lucas played for the Seattle Seahawks and the Carolina Panthers. Like most athletes, he found his first yoga class extremely challenging—so challenging, in fact, that he left before it was over. “It’s probably the toughest thing I’ve ever done in my life as an athlete,” Lucas told the Seattle Times. “I remember the first time I went, I fell out.”

Shawn Marion, Former NBA Forward

Shawn Marion’s career accolades speak for themselves: four All-Star selections, two All-NBA third team selections and an NBA championship. Marion was a beast on the court, but he was never as successful on the yoga mat. He tried yoga a number of times throughout his career, but he never made it a regular routine. Why? Because it was too hard. “That s*** is hard,” Marion told SLAM. He was not wrong.

Travis Benjamin, NFL Receiver

Travis Benjamin has long been one of the fastest dudes in the NFL. But he knew that adding durability and flexibility to his speed could increase his overall performance as a player—and this led him to take up yoga last off-season. “The first day, I was in hell. Because I didn’t know how to do anything and you see guys over there 50, 60-years old, in a better position than you! So it kind of pushed me to get to that point,” Benjamin recently told STACK.

Jared Boll, NHL Forward

Jared Boll has spent his entire career with the Columbus Blue Jackets. Prior to last season, he was looking for a way to change up his training and relieve persistent back pain. The Blue Jackets’ strength and conditioning coach turned him on to yoga, and he and a few teammates went to a local studio. They quickly realized that weight room strength has little to do with yoga prowess. “Some of the girls in the class gave us a bit of teasing, that big tough hockey players can’t make it through an hour yoga session,” Boll told Fox Sports. “It’s unbelievable how good they are at it and how hard it really is.”

Kevin Love, NBA Power Forward

Love has been a devotee of yoga since he entered the NBA, working with famed trainer Kent Katich. Yoga has helped him shape his physique and get in better tune with his body, but the benefits certainly didn’t come easy. “It might just be my hardest workout,” Love once told STACK. “Yoga can be really tough, and you can always get better at it. That’s what makes it so fun.”

 RELATED: Kevin Love’s 5 Move Yoga Workout

Shaquille O’Neal, Former NBA Center

When Shaq landed in Cleveland prior to the 2009-2010 NBA season, he was looking to increase his flexibility. “You just want to stay loose. You have to do different things to stay loose,” O’Neal told the AP. That led the 7-foot-1, 325-pounder to venture into a yoga studio for the first time in his life. He summed up his first class in ten simple words: “I’m the worst yoga student in the history of yoga.”

Tramon Williams, NFL Cornerback

A Pro Bowl cornerback for the Cleveland Browns, Williams has been practicing yoga for several years. He often attempts to recruit teammates to join him in the studio, and those who accept the invitation find that yoga can be just as taxing as a intense football practice. “It’s hard. It’s hard. That’s the thing guys realize,” Williams told the Milwaukee Journal Sentinel. “They come in thinking it’s going to be an easy day. And guys are sweating like they had a whole day of practice.”