Day one of our @bbcradiofoyle @walledmarathon #reasonforrunning series. 30-year-old Sandra Mayne shares her story.

Runners taking part in the Walled City Marathon share their reasons for taking part and tell us about the music that motivates them during the hard miles. 30-year-old Sandra Mayne is running in memory of her baby sister Caroline who had cystic fibrosis and died when she was just six months old. Sandra was two at the time. She fundraises now for CF and Derry will be her sixth marathon