She 's preparing to take on two half marathons in a week to raise money for a charity close to her heart .
Radio reporter Sian Grzeszczyk will be among those taking part .
Sian Grzeszczyk 's preparing to take on two half marathons in a week to raise money for a charity close to Sian Grzeszczyk 's heart .
Radio reporter Sian Grzeszczyk will be among those taking part .