The 42-year-old, who plays Jamie Fraser in the smash-hit, time-travelling drama series, says he often speculates about how his time as the Highland warrior could end.
In an interview with Gold Derby, Heughan said: “I think about his mortality. I think Jamie thinks about that a lot more now.”
“He’s not worried about dying, but I think it’s the consequences of dying.”
Fraser has cheated death several times since the beginning of the series, and Heughan reckons his character has used seven of his nine lives.
The Balmaclellan-born star said: “We talk about Jamie’s nine lives… I think he’s had about seven or six of them.
“Each time it costs him more, you know? It’s an interesting one because I think it’s in the scripts but I think it’s [also] in Diana’s books.”
Elsewhere in the interview, Heughan discussed his sex scenes with his onscreen wife – and the Scots heartthrob admits he ‘enjoys those moments’ with actress Caitriona Balfe.
Recalling a scene from season six, he said: “When he comes back from being away, I remember even choreographing that scene.
“He throws his jacket at Mrs Bug and jumps up the stairs and just the sheer pace of it, and the lightness he’s got in him."
“I really enjoy those moments,” Heughan added.
Earlier this year, Heughan said moving to Edinburgh as a teenager shaped him into the person he is today.
In an interview with Square Mile, a men’s luxury lifestyle magazine for London, the actor was asked if he could think of a moment or experience that influenced who he is as a person today.
He replied: “I guess when I moved to Edinburgh.
“I was living in the countryside as a young child, there were four people in my class at school. And then I moved to Edinburgh, which to me felt like a metropolis. I started going to the theatre.
“Just being in the city was really inspiring. It opened up the world to me, as a teenager. There’s a whole world out there that I want to explore.”
Heughan also recently admitted he would love to be the next James Bond, saying it’s every actor's dream to play 007.
Speaking to the Radio Times, Heughan recalled auditioning to be the iconic spy prior to Daniel Craig's official casting in October 2005.
“I met [producer] Barbara Broccoli and [Casino Royale director] Martin Campbell,” he said.
“I did a scene and they had the gun from The Man with the Golden Gun on the table and I remember thinking, ‘Wow, this is incredible’.
“It was surreal,” he added. “He’s a character we’ve all grown up with.”