The 64-year-old actor has minimal screen time as the Jedi Knight in his return to the sci-fi franchise - but that didn't matter to him because he knew Luke was central to the plot.
Speaking about reading the script for the first time, after being invited back to play Luke by director J.J. Abrams, he said: "I read the script on a little iPad with a security man with me so I couldn't take notes ... The first few words in the crawl are 'Luke Skywalker has vanished' and I thought, 'Boy, this is going to be good!'
"I thought, 'Good, I'm going to have one of those 11th-hour entrances.' I wanted impact. I wanted to affect the storyline."
Hamill returned to the franchise with other original trilogy actors Harrison Ford (Han Solo), Carrie Fisher (General Leia Organa), Peter Mayhew (Chewbacca), Anthony Daniels (C-3PO) and Kenny Baker (R2-D2), much to the delight of 'Star Wars' fans.
Hamill is currently shooting the next instalment 'Episode VIII', but admits he was initially uncertain about reprising his role as Luke, 32 years after his last appearance in Return of the Jedi.
However, he knew if he didn't return as the one-time Tattooine farm boy he would be "hated", after the rest of the original cast agreed to come back.
In an interview with The Sun newspaper, he said: "I was scared to come back ... and I'd be the most hated man in the world if I didn't do it."
Hamill can recall watching the completed version of The Force Awakens - which also stars newcomers Daisy Ridley (Rey), John Boyega (Finn) and Adam Driver (Kylo Ren) - ahead of its release in December last year and he knew instantly Abrams had captured the spirit of the space opera started by George Lucas.
The actor - who first appeared in 'Star Wars' in 1977's A New Hope - said: "The very first time I saw the film was at the premiere in Los Angeles, even though I was invited to see it before that at a little screening room. I would rather see it with a full audience.
"I thought it was amazing what they were able to do. It worked on the level for somebody who had never seen one of those films before. Everything has changed but nothing has changed. I thought my part was interesting."
