But now, Justin is getting ready to scale a much more formidable foe – Mount Kilimanjaro.
U.S. & World
The pop star will trek up the mountain in Tanzania, Africa, along with rapper Lupe Fiasco and singer Kenna, in an effort to bring awareness to the global water crisis.
"I've been training four times a week to get my VO2 [oxygen consumption] levels up to expand my lungs," Justin told GQ. "We'll climb for a week straight, carrying 30 pounds on our backs. It's going to be intense, but it's going to be so rewarding."
For Kenna, the effort to bring awareness to a worldwide danger is something that hits very close to home.
"My dad almost died as a child from waterborne diseases in Ethiopia, and he had talked to me about digging a well there, and I thought, 'I have too many friends who would be concerned with the subject of clean water. Maybe I can help out,' " Kenna told ELLE magazine in a recent interview.
And while none of the singers underestimate the journey ahead of them, Justin is confident he and his counterparts will be well-prepared.
"We're going to be ready for it," he told GQ.
Related Content from AccessHollywood.com:
PLAY IT NOW: Access Extended: Justin Timberlake Talks Rihanna's 'Rehab'
PLAY IT NOW: What Is Justin Timberlake's Wardrobe Must-Have?