How important is willpower? And how can we strengthen our self-control? Ash talks to Martin, a drug addict, now trying to kick a really bad habit. One thing Martin has trouble with is self-control. And it turns out that self-control is key to this whole conversation about behaviour change.

Ash talks to Terrie Moffit, a professor at Duke University. Terrie explains how her pioneering work on a thousand children in Dunedin, New Zealand, shows how self-control is just as important as intelligence when determining life outcomes. Does this mean we’re all doomed? Not according to John Tierney, the author of Willpower. He says willpower is like a muscle and can be strengthened like a muscle. To explain this he tells the story of the 19th century explorer Henry Stanley. Stanley developed a series of tricks and techniques to help build his willpower in the face of the hardships he found on his travels through Africa. These are the kinds of techniques we can apply to our own lives today.