orn on November 8, 1961 in Hollywood, California, Leif grew up in a world of showbiz and got his first taste of acting in the blockbuster film, Bob & Carol & Ted & Alice (1969) playing the son of Elliott Gould and Dyan Cannon, though he was uncredited. Then he was a frequent guest in TV shows such as Nanny and the Professor (1970), Family Affair (1966), Cannon (1971), Gunsmoke (1955) and The Odd Couple (1970) as well as receiving brief exposure in Walking Tall (1973) and Devil Times Five (1974), both films also starring his sister, Dawn Lyn. He then played Endy Karras in the TV series Three for the Road (1975), also starring Alex Rocco and Vincent Van Patten, and by then he started getting exposure on teen magazines and fan mail, despite the show's short run. He still pursued his acting career by starring in some westerns like God's Gun (1976), Vengeance (1977) and Peter Lundy and the Medicine Hat Stallion (1977).