The 68-year-old guitarist was diagnosed with the early stages of lymphoma cancer in 2013. That same year, the band's tour dates were arranged around his antibody treatment until the course ended in 2014.
And the band announced a few months later, during the 2013 tour, that they would embark on their final tour because of Iommi's health issues.
He told Classic Rock magazine: "Since I was diagnosed it has changed my whole life. I've had to really think about it seriously. I can't just pack a suitcase and go off and disappear around the world. I don't want to go on and keel over on stage. If it's going to happen, I'd rather be at home."
Death is something which lead singer Ozzy Osbourne has thought about, too.
He said: "We're not getting any f***ing younger - every other day we're seeing some other rock star pegging it."
A host of big-name acts have passed away recently, including David Bowie and Prince, and Black Sabbath bassist Geezer Butler admitted he is determined to enjoy his own life.
He said: "We don't want to fade out on the road. We want to go home and enjoy a bit of home life. We've been on the road for forty-eight years. It's a long time."
