MORRISON, CO – When Bol Bol got to the bottom of the steps at the Red Rocks Amphitheater, he looked up and his jaw immediately dropped. He turned to Monte Morris and asked if the group of Nuggets players on hand would have to run to the top. Morris grinned and emphatically nodded before yelling “EASY MONEY” seconds later.

The Red Rocks Amphitheater is one of the world’s most renowned music venues and a tourist attraction that welcomes over a million visitors a year. For the Nuggets, the 6,435-feet high concert hall represents something else: A rite of passage. It’s a chance for players to experience one of the toughest workout sessions available to help in acclimating to the altitude which they’ll deal with during the NBA season.

Bol was one of four first-timers with Vlatko Čančar, Tyler Cook, Tyler Zeller to take part of the Friday morning training session, joining veterans Gary Harris, Will Barton and Monte Morris. The players did the famed east stairway, climbing 145 steps and going up 300 feet in the process, four times back and forth. They also did a range of exercises on the venue’s 69 rows, doing leaps and running up 2.7 miles in front of dozens of onlookers. The veterans “welcomed” their rookies to the experience.

“[They said] you’re never coming back or first time and last time you’re here,” Čančar revealed with a grin. “It loosened up the mood and made everything easier.”

The irony of it all is sometimes what appears to be the easier workout, like going up stairs, can present unique challenges to NBA athletes.

“The hardest part is going up the stairs one by one because we're all really tall,” Bol said.

He added, “It's something different [from what I'm used to]. Even though it's not directly related to basketball, I think it'll help on the court because of conditioning and endurance. I think this helped me a lot today.”

Zeller, a player who has been in the NBA since 2012, called the workout one of the most difficult in his seven-year professional career.

“It’s up there, it’s not something you’re used to,” Zeller said. “It definitely ranks up there.”

Harris, the longest-tenured Nugget, explained why the workout is important as the team gets ready for the upcoming season.

“We play such a high and intense game, there's a lot of up and down. A lot of times, we're tired -- especially playing in the altitude,” Harris said. “This prepares us for the season.”

Felipe Eichenberger, the Nuggets’ Head Strength & Conditioning Coach, explained why the workout is an important part of the offseason workout.

“Well, it's more like a cardiovascular stimulus,” Eichenberger said. “So, any exercise that we do even if it's not a sport-specific for basketball, and this altitude, they're going to have an adaptation. Adapting their physiological system and their physiology to this higher altitude than Denver, it's going to benefit us… So that's the purpose behind everything that we do here.”

When the workout was done and the Nuggets players gathered at the top of the Amphitheatre, Harris was happy with what he saw from his rookie teammates.

“The rookies, they did a great job,” Harris said. “They came in with the right attitude, the right mentality. They killed it today.”

He then added, “It was hard [when I first did it] and it's still hard.”