Earlier this year, Jessica Biel, Emile Hirsch, [article id="1633660"]Lupe Fiasco[/article], Santigold and others banded together to climb to the [article id="1633654"]summit of Mount Kilimanjaro[/article] to raise awareness about the global clean-water crisis. Now Justin Timberlake has pitched in to support the effort.

The singer is set to provide a personal introduction to "Summit on the Summit: Kilimanjaro,"

the 90-minute documentary about the celebrities' climb that will air on MTV on March 14 at 9 p.m. ET/PT. Masterminded by Grammy-nominated musician Kenna, the team took a [article id="1629516"]six-day, 50-mile trek[/article]

to the peak of the tallest mountain in Africa.

"It was a combination of the mental and the psychological aspects of the mountain, of the slow-but-steady pace that you had to go up it, and that sometimes made your brain just want to explode, because you just wanted to get there so badly," [article id="1633659"]Biel told MTV News[/article] Wednesday. "But then you'd get this rush of inspiration of 'I'm not doing this for me. I'm doing this for something bigger than me, for people who don't have a voice, for people that need water around the world,' and then you'd power through."

In addition to raising awareness about the clean-water crisis, the "Summit on the Summit" raises funds for P&G's Children's Safe Drinking Water Program, United Nations High Commissioner for Refugees and Water for People's PlayPumps Technology. During the MTV broadcast, viewers will be able to text SEND to 90999 to donate $10 to the U.N. Foundation on behalf of "Summit on the Summit." Each donation will send 1,000 liters of clean water to people in need.

"MTV has a long history of educating its audience to raise awareness on issues that are important to them," said Dave Sirulnick, Executive Vice President, News and Docs. "More than 1 billion people worldwide do not have access to safe, clean drinking water. By airing this documentary, MTV hopes to mobilize a new generation of young people who may not be aware of this global cause and take action to get involved in helping find solutions to the water crisis."

Don't miss "Summit on the Summit: Kilimanjaro," airing Sunday at 9 p.m. ET on MTV. And find out what you can do to help solve the global water crisis now at the "Summit on the Summit" Web site.