Jermain is not alone in lending his support to Sport Relief 2008. Stars such as Leona Lewis, the Spice Girls, Davina McCall, Alan Shearer, James Cracknell, Tess Daly and Mark Ramprakash are also behind this year's campaign.
Sport Relief 2008 is all about challenging yourself, friends, family and colleagues to do something sporty and raise cash.
The ultimate challenge for the public is doing the Sainsbury's Sport Relief Mile where hundreds of thousands of people across the UK will take to the streets and go the distance for Sport Relief. Last year David Walliams swam the Channel. This year participants can set their own challenge by having the choice of running 1, 3 or 6 Miles and can sign up for their nearest mile at www.sportrelief.com.
Olympic gold medal winning rower, James Cracknell will be taking the lead in inspiring the nation by undertaking a momentous challenge whereby he travels from England to Africa under his own steam. Alan Shearer and Adrian Chiles will also be rising to the challenge for Sport Relief when they take on a Newcastle to London cycle ride.
Live coverage from the Mile events will be shown during The Sport Relief Mile Show on Sunday 16th March on BBC ONE, with those participating being the stars of the show.
Sport Relief harnesses the power and passion of sport to change lives for the better. Comic Relief spends the money raised to help vulnerable people living incredibly tough lives both at home in the UK and across the world's poorest countries.
Jermain Defoe helped kick off Sport Relief 2008 by putting CBBC Newsround presenter Gavin Ramjuan through his paces at Spurs Lodge training ground today. See them in action tomorrow (Tuesday) at 7.25am on CBBC Channel, 8.25am on BBC TWO and again at 5.25pm on BBC ONE.