Michael Richards was “motivated” to write his memoir after beating prostate cancer. The ‘Seinfeld’ actor used his autobiography ‘Entrances and Exits’, released on June 4, to reveal he waged a secret battle with the disease after he was diagnosed with it in 2018. He has now told Hoda Kotb, 59, in a rare sit-down interview on the ‘Today’ show about how he drew a positive from his health fight: “I made it – I beat it – and that certainly motivated me to get into the book because I went through a big review of my life.” The actor also revealed he was so riddled with insecurities he never watched h…