The "SexyBack" singer is currently preparing for a week-long trek up Mount Kilimanjaro - the world's largest free standing mountain - with rapper Lupe Fiasco and US singer Kenna to raise awareness of the global water crisis.

He said: "I've been training four times a week to get my VO2 - oxygen consumption - levels up to expand my lungs. We'll climb for a week straight, carrying 30 lbs on our backs. It's going to be intense, but it's going to be so rewarding. "We're going to be ready for it."

Ethiopian-born Kenna - real name Kenna Zemedkun - recently revealed he came up with the idea to bring awareness to something close to his heart.

He said: "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.' " The three musicians are not the only celebrities embark on a gruelling charity trek up the Tanzanian mountain recently.

Last month, nine British stars - Girls Aloud singers Cheryl Cole and Kimberley Walsh and Take That musician Gary Barlow - raised millions

(China Daily/Agencies, April 16, 2009)