Arnold Schwarzenegger wants to make something perfectly clear: He harbors absolutely no ill will toward James Cameron for opting not to direct

Terminator 3.

"Jim told me he's just too busy, and I totally understand his point of view," says Schwarzenegger, whose latest actioner, The 6th Day, opens Friday. "We are such good friends that we have total respect for each other."

Schwarzenegger initially was dead-set against doing T3 unless the Oscar-winning filmmaker returned to the helm. (Fight Club's David Fincher is now on board.) "I changed my mind," he admits. "The script was really good, and I thought that it ought to be made."

Another film Schwarzenegger is feeling passionate about is the sequel to his 1990 blockbuster Total Recall. Unfortunately, unlike his 6th Day alter ego (who clones himself), Schwarzenegger is only one person. "Unless I clone myself for real, I can't do all these sequels to the Terminator and Total Recall at the same time," laughs the actor, who is slated to begin work on T3 this spring. "You can only do one movie a year if you really want to be a part of it from beginning to end. That's what makes it fun for me. I don't want to come in and be a hired hand like some actors."

As it is, the 53-year-old — who underwent surgery in 1997 to correct a congenital heart valve condition — admits that life as an action hero is beginning to take a heavy toll. "When you get to be over 50, it is not as easy anymore to recuperate your body like when you were 20," he sighs. "On The 6th Day, one of the most trying scenes was just running up some steps. We shot from 8 at night until 6 in the morning, and I was running up those same steps. There was like 52 steps."

"I had to focus on something else," he continues. "I tried to think of going on a great ski trip, so I could get motivated each time to run up those stupid steps."