He said his first suspicion "that was going to be it" started as early as when he signed on to continue his roles through Seasons 11 and 12 of "The Big Bang Theory," as he juggled multiple personal and professional incidents in his life at once.
In what he calls "an intense summer," along with playing the hilarious and intellectual physicist on the award-winning sitcom, Parsons also traveled to New York to perform on Broadway in 2018 along with committing to commercial shoots.
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"It was a complicated road, as you can imagine," he said. "We went through the 11th season, and then that summer, I went to New York to do 'Boys in the Band' on Broadway, and I think anything I felt got really affirmed."
Parsons' biggest wake up call, however, was a much more emotional one: the death of his dog, which he referred to as "the end of an era."
"I was exhausted, and I was really upset about one of our dogs was getting really at the end of his life around then," he said. "I'll never forget that walk around the park to let him go to the bathroom before we went for the commercial shoot. He just looked so bad, and I was so tired, and (my husband) Todd was like … 'we gotta go, we've scheduled this, they've fit everything around your schedule.' And I just started crying."
He tearfully admitted he feared "this dog's gonna die while I'm off working, and I'm gonna feel so bad," revealing their decision to put their 14-year-old dog to sleep that summer.
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Parsons said he had to simultaneously cope with an injury, after he slipped and broke his foot during a Broadway curtain call.
"It was the scariest moment for the next couple of days, cause 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've done if I couldn't have gotten back on for the play. But I did."
In addition to his dog's death and broken foot, Parsons attributes his final "moment of clarity" leading to his departure to his reflections about his late father. The actor realized that by the end of season 12 of "The Big Bang Theory" in May 2019, he would be 46 – six years younger than when his father died at age 52.
When leaving the show, he says he told "Big Bang" writers Chuck Lorre and Steven Molaro that "if you told me that like my father I had 6 years left to live, I think there's other things I need to try and do."
As Parsons got emotional discussing his departure from the show, he took a moment to appreciate his cast mates, saying that it was "a complete joy" working with the team for over a decade.
This article originally appeared on USA TODAY: The Big Bang Theory: Jim Parsons on why he exited as Sheldon Cooper