Kenan Thompson gets candid about his life and career in his new memoir, When I Was Your Age: Life Lessons, Funny Stories & Questionable Advice from a Professional Clown.

The Saturday Night Live star, whose tell-all memoir published today, told PEOPLE, “Certain things just have to be told because I’ve never told them before, you know what I’m saying?”

“So, if you’re going to write a memoir, you might as well just lay it all out there,” he said.

Thompson discussed about his early days as a Nickelodeon child star on shows like All That and Kenan & Kel and SNL in his new memoir.

The comedian also wrote his past hardships, his struggles with body image, his early insecurities on SNL and his previous estrangement from his Good Burger co-star Kel Mitchell.

He revealed, “It is terrifying to open yourself up like that because I guess I’ve not had to do that, you know what I mean?”

“I have always been so performance-heavy. I haven’t had to do a whole lot of, ‘Let me explain where Kenan is now’ kind of stuff’,” remarked the 45-year-old.

Meanwhile, Thompson talks about his marriage to ex-wife Christina Evangeline in her new memoir, writing, “She had an excitement for life, and was the outgoing version of myself that I wished I could be on a daily basis. It’s complicated, as all relationships are.”

Reflecting on being a single father, Thompson added, “I love having my girls around me. I used to be such a fly-by-the-seat-of-my-pants kind of guy. I hated planning and liked to be spontaneous. When I became a father, I had to throw that all out the window.”