FORT WORTH -- Trying to reach North America's highest peak isn't something one does on a whim, or without any preparation.
Six Fort Worth firefighters are training for the trek in late June.
News 8 first introduced the fun-loving group last week. Before they leave, the men are undergoing rigorous workout routines.
At least once a week, they train together in a high-intensity, no-rest circuit which includes wall balls, burpees, and jumps.
They have also spent hours lugging around 50-pound backpacks, and even free-weight sleds to simulate the real sleds they will haul across the icy Alaskan landscape at Mount McKinley.
The workouts attract a far amount of curiosity.
"You get some crazy looks, honks, but really everyone has been overwhelmingly positive," said firefighter Kasey Gandy.
The pain here will be a gain as the men ascend some 20,000-plus feet of the mountain.
Thin air, coupled with layers of clothing and sporadic weather, make for an unpredictable environment where everyone's body reacts a little differently.
"When you decide to climb a 20,000-foot mountain, you've got to ramp up your training," said firefighter Dusty Sides, who has mountain-climbing experience.
The group is climbing on behalf of six burn survivors from Sons of the Flag. The burn victims will write each fireman a letter of encouragement which they will read as they approach the summit.
The firefighters are hoping to raise $10,000 for the cause. For more information on donating, click here.