"It worked with my chemo schedule, so that's why we were able to do Glastonbury."
Holly Wellington was diagnosed with breast cancer a year ago - but she's now got the all-clear.
The 26-year-old singer from electronic jazz group Ishmael Ensemble told Radio 1 Newsbeat music got her through a difficult period in life.
"I spent most of the time on the sofa or in hospital and had such little energy. But whenever I did, I'd put it into performing," she says.
Holly spoke with us from the Royal Albert Hall, where her band are playing a gig for Teenage Cancer Trust.
