Help needed by chronic negative thinker ...?

hi i have just turned 38 . i am a chronic negative thinker . it makes me really ill sometimes ( say once a week ) . i was an alcoholic due to it but i gave it up at 27 . i work hard and am called intelligent by friends / handsome by women . i started by reading norman vincent peale at age 22 . i have gone on to tony robbins , chicken soup for soul etc .... to change i am required to be positive for at least a day .. i find it difficult to be positive for a minute . i have tried meditation but i cannot sit still because of worry . i am at my wit's end . i am taking zoloft for last 4 years . it has made me little better to carry on day to day work well . but i realise all the time that i could be much more successful at everything with little bit of optimism ........ can anyone suggest any thing to make me positive for a couple of days .. once that is done i will bootstrap myself i am confident .... ( please do not ask me to look at babies .. the only thing i refuse to do !!!! )