Jackman - soon to be seen in X Men: Days Of Futures Past - told how he has to spend six months training to get into shape for his role as the mutant superhero.
Due to the frequency of his appearances, he had spent a total of 18 months keeping his body in check for his most recent stint as Wolverine.
His co-star Michael Fassbender - also a guest on the chat show - praised his colleague's commitment to the gym.
"His discipline is incredible - he is up and in the gym at 4.30 in the morning, every morning,'' Fassbender said. "When we arrived there was a 'Jackman' effect and we all started training to try and keep up.''
Watch the trailer for X Men: Days of Futures Past here:
- AAP