As much as fans are (hopefully) preparing themselves to be wowed by James Gunn’s space opera Guardians of the Galaxy, they should also be ready to fall in love with a talking extraterrestrial tree, aka Groot, voiced by Vin Diesel. The most impressive thing about Groot, in addition to the incredible animators who virtually brought the character to life, is that Diesel manages to convey a wide range of emotion with just three words of speech, “I am Groot.”

When Screen Rant sat down with Diesel recently, we asked him about his methods for conveying different emotions in three words and he surprised us with a little demo of the additional sound effects he came up with to enhance his performance.

I keep saying this to everyone, but this movie is so good it’s all I can talk about.

You know I say this and you’re going to identify this because not everyone has seen the movie, but I walked out of the movie going, ‘Did I have that much fun?’ You must have had so much fun that you had to say, ‘Did I have that much fun? Because I did.’ ‘Why did I love that movie?’ I loved that movie.

I’m wondering, because it’s so amazing to hear different emotions just with those three words, I’m wondering when you’re looking at something like this, what’s the tone you take?

Oh my God with a scene like that I might not even get the three words. I’ll watch it over and over again and try to make sounds you wouldn’t normally make, and it could be just like an exhale, but done with a little melody to it (sighs). That one is the same thing, you know, what you’re pointing to is something very interesting. What I’ve been talking about all day is the fact that this character is limited to only three words, but there’s almost this whole other vocabulary created of grunts and sighs, inhales and exhales, that filled the character at moments there weren’t lines. It was really an interesting exercise. I can imagine all my old acting teachers saying, “You want the biggest challenge in the world?” No mannerisms, no physicality, you’re limited to these three words and that’s all you can do in all these situations and scenarios no matter what circumstances your character finds himself in, that’s all you got.

Vin Diesel at GOTG Premiere

How about this one? Are you just letting it rip?

Yeah that was a huge let it out, I could’ve taken down the building with that Groot roar. Dangerous, you don’t want to be around Groot at that time.

Well we’re out of time but I’m so glad you campaigned to do this one 

I am so excited about it, I feel lucky. James Gunn is really amazing, Kevin Feige was, earned his ‘brilliance’ reputation with this one.

More: Chris Pratt Video Interview

Guardians of the Galaxy is directed by James Gunn and stars Chris Pratt, Zoe Saldana, Dave Bautista, Vin Diesel as Groot, Bradley Cooper as Rocket, Lee Pace, Michael Rooker, Karen Gillan, Djimon Hounsou, with John C. Reilly, Glenn Close as Nova Prime Rael and Benicio Del Toro as The Collector.

Guardians of the Galaxy opens August 1, 2014.