Michael Madsen at the Premiere of 'Vice' held at Grauman's Chinese Theatre. Hollywood, California - 07.05.08

The Reservoir Dogs star admits he has never been healthier after training hard with no-nonsense boxing trainer Michael Norman Kelly for fight film Strength + Honour - and now he feels terrible if he doesn't keep up his work-outs.

Madsen explains, "It was really hard to get in boxing shape and the last thing I want to do is try to get there again. It's a lot easier to maintain than it is to get back.

"I have stayed in shape and I have continued to work out. It's good for your head. When you get your body in shape your mind will follow. It's the most physical dedication than I've ever done for a role. You can't fake it.

"I learned a lot from the guy that trained me, Michael Norman Kelly, who was a middleweight in Ireland. He came to California and gave me my first lessons, hitting the speed bag and the skip rope before I went to Ireland. That was a good start for me.

"After a while you kind of get mentally and physically addicted to the endorphines of fighting and training, so much so that when we were done with the picture, when I wasn't working out I started to feel like a chump. I wanted to keep going in the gym and keep staying in shape. It changed me as a person."

Source: WENN