Lessing wrote actively for television from its pioneering days in 1950 in New York, and moved to California to continue his career until 1979. Shows he wrote screenplays for include Hawaii Five-O, The Fugitive, Lost in Space, Bonanza, The Nurses, The F.B.I., Baretta, Cannon, Dragnet, Eight is Enough, Shirley Temple's Storybook, The Adventures of Ellery Queen, and The Man from U.N.C.L.E..