 Working alone as a graphic artist , Hartman frequently amused himself with " flights of voice fantasies " . Eventually he felt he needed a more social outlet and in 1975 , aged 27 , developed this talent by attending evening comedy classes run by the California @-@ based improvisational comedy group The Groundlings . While watching one of the troupe 's performances , Hartman impulsively decided to climb on stage and join the cast . After several years of training , paying his way by re @-@ designing the group 's logo and merchandise , Hartman formally joined the cast of The Groundlings ; by 1979 he had become one of the show 's stars . 
