He's played a doctor on Shortland Street and a keen marathon man on Nothing Trivial - now life is imitating art for Will Hall.

The well-known Kiwi actor has vowed to help kids with Type 1 diabetes by running four half-marathons before he turns 40 - and wants to raise $4444.40 doing it.

Hall - who is the first to admit he's "not built for running" - has just finished a half-marathon and has three more to go in his quest to raise awareness about a new device that can change the lives of children with the condition.

Hall's 5-year-old