Ed Helms says it was "beyond a no-brainer" to sign up for The Lorax.

The Hangover actor asked to be cast in the animated 3-D movie - an adaptation of Dr. Seuss' children's tale of environmental conservation - because he was such a big fan of the book when he was a kid:

"It was beyond a no-brainer - it was something that I actively pursued. I grew up hearing the story of The Lorax frequently. My mom was a huge Dr. Seuss fan and just read all of that stuff to us all of the time. The Lorax was a favorite. When I heard they were gearing up development on The Lorax, I asked for a meeting and if there were any part in the movie where I might just fit in, no matter how big or small."

The 38-year-old actor - who will star alongside Taylor Swift (Audrey), Zac Efron (Ted) and Danny DeVito (Lorax) in the movie - was "floored and insanely excited" when he was eventually told he had one the main parts in the film.

"A couple of months went by and I didn't know what was going on. Then they called with that offer and I was floored and insanely excited," he added in an interview with The Huffington Post.

The film follows 12-year-old Ted as he sets out to find a real Truffula Tree in order to win over Audrey's affections, and on his journey he meets the Once-ler, who tells him all about the story of the Lorax.