The Big Bang Theory's Jim Parsons was recently a guest on Doctor Who alum David Tennant's podcast, and if that sentence isn't enough to get your nerd senses tingling, this next one will. The actor behind the beloved Sheldon Cooper ended up telling Tennant why he quit The Big Bang Theory after 12 years.

"Our final contract was for the last two years, but no one knew when we signed it what that would mean. I kind of had a suspicion in my heart that that was going to be it for me when I did sign that contract, but you never say never and who knows," he said, going on to reveal that the decision to leave the show solidified the summer before they started filming Season 12. "I was exhausted, and I was really upset about, more than anything, one of our dogs was getting really at the end of his life around then."

Parsons was also busy performing a play in New York at the time and remembered being afraid that his dog would die while he was at work. He and his husband ended up making the decision to put their dog to sleep at home, the memory of which still upsets him to this day. A few days later, Parsons slipped and broke his foot whilst on stage. 

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"It was the scariest moment for the next couple of days because I didn't know — I felt like I was at the edge of a cliff, and I was teetering, and I saw something really dark below between the death of the dog, and I don't know what they would have done if I couldn't have gotten back on for the play."

Parsons did get to go back on stage (with a boot), but he tearfully revealed to Tennant that it was a "really intense" summer. He also mentioned that his father had passed away at the age of 52, and Parsons realized that at the end of Season 12, he, himself, would be 46-years-old. All of this compounded to give him a pretty important realization. 

"I had this moment of clarity that I think you're very fortunate to get in a lot of ways, of going 'Don't keep speeding by.' You know? 'Use this time to take a look around.' And I did. I was like, 'I gotta make a move,'" Parsons said. "And this is what I said to Chuck Lorre and Steve Molaro when I talked to them when I went back to work next year. I said, 'If you told me that like my father, I had six years left to live, I think there's other things I need to try and do.'"

Since the show ended in May of 2019, he has teamed up with his The Big Bang Theory co-star Mayim Bialik to produce a new comedy series (starring Bialik) titled Call Me Kat and scored an Emmy nomination for his turn in Ryan Murphy's Hollywood, now streaming on Netflix. 

The Big Bang Theory is currently streaming on HBO Max.

Jim Parsons, <em>The Big Bang Theory</em>Jim Parsons, The Big Bang Theory