TORONTO -- Montreal director Jean-Marc Vallee says his acclaimed new film "Wild," based on Cheryl Strayed's bestselling memoir, is a tribute to his late mother.

Like the ever-positive ailing matriarch played by Laura Dern in the drama, which is at the Toronto International Film Festival, Vallee says his mother was also strong and uplifting even while battling cancer.

"I lost my mom of cancer three years ago, so of course I related to the material," he said in an interview. "I was crying like a baby when I read the book and I said, 'Yeah, I'm going to make this film and really pay tribute to my mom and to this kind of female strong character."'

Star/producer Reese Witherspoon is stirring up early Oscar buzz for her role as Strayed, who tries to flee her reckless and drug-addled past through a soul-searching and arduous hike spanning 1,600 kilometres along the Pacific Crest Trail. Guiding her through her journey are the memories of her late mother, Bobbi (Dern), who always had a sunny disposition and encouraged her to try to find her "best self."

Nick Hornby wrote the big-screen adaptation that was critically lauded when it made its world premiere at the Telluride Film Festival just over a week ago.

"My mom was a Bobbi," said Vallee, "always so positive and annoying me with her 'rich in love' and 'you can do it,' 'don't worry, life is well-made and God is there for you and life will take care of you.'

"These strong women who devote their lives to their children and just loving their children and forgetting about themselves, and their mission on this Earth became, 'I'm going to be there for them.' It's rare that you see a man in that position. It comes mostly from a woman, from mothers, therefore from women. I mean, there are some fathers, yeah, it's strong. I'm a father.

"But there's something about the connection with the mother."

Vallee said the film is also a tribute to women like Strayed.

"What a character. ... Here's a film about a woman where she doesn't define herself through the eyes of a man, she's not with a rich man, she has nothing. At the end of the film she has 20 cents in her pocket, no job, no house, no apartment, no man, no relationship, no parents, and it's a beautiful ending."

It was Witherspoon who ignited the adaptation.

The best-actress Oscar winner for "Walk the Line" said she read Strayed's book several months before it was published and knew immediately she wanted to do it.

It was her husband, Jim Toth, who suggested Vallee. Toth is a talent agent who represents Matthew McConaughey, star of Vallee's last hit film "Dallas Buyers Club," and told Witherspoon about the director.

"We sent him the script and he called us immediately and we talked over Skype and we both cried," said Witherspoon at a press conference Monday. "We immediately connected over the material."

"I just knew immediately it was Jean-Marc because he was so enthusiastic about the parts that were the most frightening," she added.

Vallee pushed Witherspoon in ways she hadn't been before.

For instance, he insisted the massive backpack she uses throughout the film be just as heavy as it is in the story.

"When I first showed up on set I thought, 'For sure, I've been on movies before. They just stuff newspaper in the back and it won't be heavy. It's no big deal,"' said Witherspoon. "And Jean-Marc immediately was like, 'Why does the backpack not look heavy on your back?' I was like, 'Well, because I'm going to pretend that it's heavy!' He said, 'No, no, it actually has to be heavy,' and I was like, 'You're kidding, right? This has got to be a joke.'

"It was great, though, because it actually did change the way I walked and it changed the way it dug into my shoulders and how quickly my body got tired from carrying this thing," she added. "And then after 5 1/2 weeks of carrying it on my back, I got so used to it.

"It was like an appendage and I missed it when it was gone."

Vallee also insisted Witherspoon wear no makeup and not have her hair styled, and that the mirrors in the hair and makeup trailers be covered.

"It was raw. I've never seen myself in a movie like that before," said Witherspoon, looking the opposite of her "Wild" character in a chic white dress.

"I was like, 'But if Cheryl could be brave enough to tell every part of her story, I had to be brave enough to throw away my vanity and go for it."'

Vallee was at the Toronto film festival last year with "Dallas Buyers Club," which went on to receive six Oscar nominations, including a nod for best picture. It won three, including best actor for McConaughey.

His next project is "Demolition" with Jake Gyllenhaal and Naomi Watts. He said he then plans to shoot another film next September, followed by a French feature and then a French-Canadian project in Montreal.

"I've got the next four years lined up," said Vallee, whose other films include "The Young Victoria," "C.R.A.Z.Y." and "Cafe de Flore."

"I'm doing indie films. I'm not doing the Hollywood big thing. I'm picky in my choice -- choosing your film is choosing your lifestyle. You've got to wake up and be happy.

"I haven't made all the right choices before in my life, but now I think I'm choosing wisely."

The Toronto International Film Festival runs through Sept. 14.