[James]

For participants, the trips can sometimes be an epiphany. Sissy Rooney joined a trek in the Mexican rainforest in May on behalf of Children in Crisis - rather a different challenge to being a housemate on Big Brother 4 last year. 'It was the hardest thing I've ever done,' she says.

'By the second day, I had cuts all over my ankles, I was covered in mosquito bites and I wanted to go home. But after a day or so I really got into it. We became really close in the group, and the sense of achievement was incredible. It's one of the most rewarding, satisfying and enlightening experiences that I have ever had.'

From http://observer.guardian.co.uk/trave...350656,00.html