I suspect the growth hormones and steroids he took when lifting probably didn't help (he was huge in The Scorpion King, but the tell tale signs are quite apparent). He cleaned up, turned veggie, lost a load of weight, got seriously fit (he'd go jogging with a tractor tyre tied to a rope around his waist and dragging behind him!) and karked it!
He was famous as the actor that gave 5 dollars to anyone who could remember his name before he'd sign an autograph.