The 56-year-old actor explores reincarnation in his new film 'Cloud Atlas' - which also stars Halle Berry and Ben Whishaw - and although he strives to live for the present, Tom doesn't believe in past lives affecting the a person's future.
He told the Metro newspaper: "I think [past lives] is a bunch of baloney and malarkey. I'm known to be cranky in that way.
"Look, I believe in the importance of the right now and although I'm perfectly willing to envelop myself in the mystery of it all.
"As a layman who reads history, I can see that the human condition does not evolve until someone does the right thing, which is a version of saying, 'It's important the karma you put our right now because it's going to affect eternity.' "
Tom - who has children Colin and Elizabeth with ex-wife Samantha Lewis, and sons Chester and Truman with current spouse Rita Wilson - is "proud" of his determination to get where he is today, which all began when he upped sticks from California and drove to New York to begin his career in 1979.
He said: "Individual jobs come and go but the fact that I had the courage to do that is the thing I am most proud of.
"Most people would have been afraid to do that. I was about to have a kid, which I found out halfway across the country. But rather than listen to all the reasons why I shouldn't do it, I adhered to the one reason why I should; it's going to be fun."