The scenes on Ahch-To were filmed not with a green screen, but on location at the peak of Irish island Skellig Michael.
Walking to the top was an arduous task, and one that could have been pretty dangerous given the steep, harsh steps.
The Luke Skywalker actor told SFX: “I said ‘How long are you allowing the crew to get up the hill?’ They said, ‘45 minutes.’ I said, ‘Give me an hour and a half.’
“I had to stop every 100 steps because they’re not normal steps – they’re stone, and it’s up and up and it never ends.”
He added: “They had this big mountain climber guide behind me to catch me in case I stumbled and fell.
“If I fall off the cliff and die, the insurance would go crazy – let’s face it, I’m an investment!”
There is a great deal of speculation on Luke’s headspace in the new film, with many wondering if he has succumbed – at least in part – to the Dark Side.
Whatever the situation, he’ll be spending at least the first chunk of the movie with Daisy Ridley’s Rey, following the clifftop cliff-hanger of 2015’s Episode 7.
Hamill won’t, it seems, be back for the newly-announced next trilogy, which Last Jedi director Rian Johnson will take charge of.
Johnson was unveiled this week as the man behind the next series of films, which will be completely separate from the Skywalker saga.
Star Wars 8: The Last Jedi is out on December 14 in the UK.