The `Expendables` actor - who married lingerie model Emma Heming in March 2009 - admits he had ruled out ever finding love again after his divorce from Demi Moore in 2000, and credits the British beauty for turning his life around.
He said: "I`m the happiest I`ve ever been and this comes after a long period of being kind of lonely, even though I tried to convince myself I was enjoying my life.
"Before I met Emma I was very pessimistic about finding that special woman with whom I would want to spend my life with.
"I thought it would be difficult for someone like me, who is well known, to find a woman who didn`t have an agenda and who just wanted to be with me because they loved me, pure and simple."
The actor also admitted he struggled with the break-up of his 13-year marriage to Demi, but after receiving advice from Will Smith, realised they should stay on good terms with the actress and her new husband Ashton Kutcher for the sake of their daughters Rumer, 21, Scout, 18, and Tallulah, 16.
He explained in an interview with The Sun newspaper: "I just saw that there`s no point to living with regret or antagonism or having any pent-up anger. You have to let it all go. It was a tough time for me during those years after the break-up. But I had a long talk with Will Smith one day.
"He kind of explained to me how I had to make an effort to be good friends with Demi for the sake of our girls and how they would have a much happier life and feel so much better if Mom and Dad could stay friends. That was a great decision in my life and to tell you the truth it worked out really well."