John Joseph is an Iron Man athlete. 

He is also the singer of legendary Punk band the Cro-Mags and a best-selling author too.

Growing up as a homeless teenager in New York, John was a heroin mule, working the punk clubs of the Lower East Side.

He became a violent criminal and eventually a prisoner.

If crime, fighting and drugs are all you have ever known, how do you change who you are?

John's story will shock and enthrall you.

As told to Sam Walker