The 60-year-old was determined to behave like a top athlete during shooting.
He says, "There is only so much energy in the body, and I know some athletes in the film didn't adhere to the ban, but I did because I knew it was the only way.
"I hear David Beckham says he doesn't but maybe he's the exception.
"The people I know who fight all stick to a sex ban because, if they don't, they lose. Of course it is hard to do, but that's why you fight so well.
"You are so aggravated you just want to get it all over with."