Jim Parsons finds making the 'Big Bang Theory' spin-off to be ''very moving''.

The 44-year-old actor - who stars as the socially awkward Sheldon Cooper on the popular US sitcom - serves as the executive producer and narrator on 'Young Sheldon' and has admitted making the prequel series about his character has been an emotional experience for him.

Speaking at the 2017 TCA Summer Press Tour, Jim explained: ''It was very moving to me to see this machine take off that's related to all that.

''I never felt, in the 10 years that we worked on the 'Big' show, that we ... I can't talk! You don't think you're putting together these kinds of things that will add up to something like [the prequel].''

And executive producer Chuck Lorre - who created 'The Big Bang Theory' alongside Bill Prady - is similarly enthusiastic about the concept.

He said: ''It just felt like the greatest idea in the world.''

Sheldon's history has already been explored in some detail in 'The Big Bang Theory', including the death of his father.

But the spin-off is set to show how ''people change and they grow and develop over the course of many years''.

Of an upcoming storyline about Sheldon's father, Chuck said: ''Seasons can take place over a couple of months. We have a lot of freedom with the backstory.

''We're going to show there was a great deal more to the man than we discussed over the years on 'Big Bang'.''

Meanwhile, Jim also admitted he's loved working with 'Big Little Lies' actor Iain Armitage, who has the title role on the prequel.

He said: ''I was able to interact with Iain a lot and discuss things that were peculiar to the character.

''Though that I have to tell you it was a very moving experience to me to see something I've put in a decade of my life toward.''