Kellan Lutz jokes he can't match rival Hercules Dwayne Johnson's physique.

The two actors play the Greek hero in separate movies, and the Hercules: The Legend Begins star joked his body could never match up to The Rock's.

"I wanted to get big, but then you have The Rock playing in the other Hercules. There's not enough 'extra-curricular' stuff for that," he told E! News.

The 28-year-old star has still put himself through a tough and ''rigorous'' training regime to getting into top shape for the film: "I wanted to put on weight. Renny [Harlin] the director, he just wanted me cut, so I had to get cut ... For me, it was very rigorous training. I had to learn how to ride a horse while wielding a sword and fighting mercenaries, as well as giving a badass speech and in the rain. And horses don't like the rain. It was very rigorous."

Kellan also revealed while he can't match the Hercules: The Thracian Wars star in terms of his physique, he's been glad to let himself indulge in some sweet treats on set: "If you've ever been on a movie set, there's food all the time. It's hard to stay healthy because I had milk chocolate bars three times a day, and I'd just eat the whole bar."