Mark Wahlberg insists a hotel room is ripped out and converted to a gym wherever he stays.
The 'Fighter' actor is so dedicated to staying in shape, he wakes at 2.30am six days a week to fit in two hours of exercise before breakfast and goes to bed at 8pm every night to stay fresh.
Recalling a recent visit to the actor's home, Piers Morgan wrote in his diary for Event magazine: "We discussed [Mark's] legendary fitness regime. He revealed that when he's on location, his team gut a hotel room and create a private gym for him.
"'Talk me through an average day when you're filming,' I said.
" 'I wake at 2.30am, and do an hour's hard workout from 3am to 4am, with ten-second breaks. Then we drive to a local basketball court and do two-on-two for an hour.
"'I come back to the hotel at 6am and have a plate of chicken and vegetables before heading to the set around 7am. I do 500 sit-ups through the day in my trailer to keep fresh.
"'I finish at 6pm, go back to the hotel and do 45 minutes' boxing. Then eat and go to bed by 8pm.' "
Mark - who relaxes his regime on Sundays so he can go to church - was arrested numerous times as a teenager, was addicted to cocaine by the age of 13 and even served a stint behind bars for assaulting a man when he was 16.
And the 43-year-old actor - who has children Ella, 11, Michael, eight, Brendan, six, and five-year-old Grace, with wife Rhea Durham - admits he is amazed at how well he has turned his life around.
Piers added: "'Did you ever in your wildest dreams imagine your life would end up like this?' I asked, as we stood in his cellar. 'No! I should be buried under this, not owning it.'
"He wasn't joking."