He was one of the biggest child stars in the early noughties – just don’t ask Frankie Muniz what took place while filming Malcolm in the Middle.
The 31-year-old actor - who played the main character in the sitcom - has memory loss after suffering nine concussions and several "mini-strokes".
The actor is now taking place in the US version of Dancing with the Stars, and revealed in a rehearsal video that he feels “sad” about the memory loss.
"It makes me a little sad. Things pop back into my mind [that] I should have remembered,” he said.
Despite his memory loss, Frankie is "happy" with the acting career he's had, which also saw him appear in Arrested Development, Dr Dolittle2, andLizzie McGuire.
He said: "Truth is, I don't remember much [of my time on 'Malcolm']. It almost feels like it wasn't me.
"My most memorable year is 2017, because I learned to live in the present.
"I'm happy with my acting career, I'm happy with the decision I made to drive race cars and to focus on music. Even if I don't remember it all, I'm happy."
The actor-turned-race car driver and his girlfriend Paige write down what they do together to ensure he doesn't forget.
He added: "Like, I should have remembered going to Australia. That's something that people remember."
Bryan Cranston, who played Frankie's on-screen father Hal in Malcolm in the Middle, has been amazed by his former co-star's career path and often reminds him of certain episodes of the sitcom.
Speaking on the clip, he added: "Frankie was a TV star, then he became a race car driver, and then a drummer in a rock band. I said to him, 'What are you going to be next, an astronaut?'
"They are still [his] experiences. My job is to tell him to remember what happened on Malcolm in the Middle. What a life."