Sylvester Stallone is reflecting on his tumultuous life in a new Netflix documentary "Sly." 

Featuring interviews with Stallone as well as friends, family and contemporaries like Arnold Schwarzenegger and Henry Winkler, the Golden Globe winning actor revisits his past and shares some surprising confessions in the process. 

Though he admits to having "regrets" early in the documentary, Stallone ends on a positive note after exploring the ups and downs of his life.

 "I’m in the hope business," he declared. "And I just hate sad endings. Shoot me."

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Sylvester Stallone posing in front of signage for his documentary

Sylvester Stallone said in his documentary, "Sly," that even with ups and downs, he's "in the hope business." (Ryan Emberley/Getty Images for Netflix)

Below are some of the biggest revelations from "Sly."

Difficult Parents

Born in 1946 in Hell’s Kitchen, New York City, Stallone had a troubled childhood with his parents, Jackie and Frank Stallone Sr.

Stallone described his mother as being worried about having a child, "even though she was nine months pregnant," and said that "she kept riding around on the bus. And she [went] into labor."

He continued, explaining the origin of his trademark crooked smile and slurred speech. 

"Somebody was smart enough to get her off the bus, they carried her into a charity ward. And that’s where I was brought into the world via this accident, which kind of paralyzed all the nerves on the side of my mouth. So I was born with this snarl." 

Stallone described "a certain ferocity" to his father, and his brother Frank Stallone Jr., recalled hearing their parents fight regularly.

Frank Stallone and Sylvester Stallone posing together

Frank Stallone Jr. and Sylvester Stallone both recalled their difficult childhood with their parents in the documentary, "Sly."  (Ron Galella/Ron Galella Collection via Getty Images)

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"I was raised by a very physical father," Stallone said. 

"I was no stranger to serious pain," he continued, adding, "I think it just became, ‘I’m not gonna break.’"

Frank Jr. noted their mother also took part in abusive behavior.

"Our mother was pretty bad too," he said in the film. "She was pretty handy with the old hairbrush… she had these long nails that would never break." 

Before their parent's divorce, Stallone and his brother both recalled often spending time in boarding houses while their parents ignored them. Stallone suggested that seeking validation from an audience stemmed from that parental neglect. It also helped keep him strong as he struggled to make his break in Hollywood.

Jackie Stallone walking the red carpet with Sylvester Stallone

Stallone with his mother, Jackie, in 1996 at the premiere of his film "Daylight."  (Ron Galella, Ltd./Ron Galella Collection via Getty Images)

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Family Jealousy

After his parents split, Stallone lived with his father in Maryland while his brother, Frank Jr., lived with their mother in Philadelphia. 

While living in Maryland, Stallone started playing polo and became a nationally ranked player by age 13.

However, Frank Stallone Sr. appeared to be jealous of his son’s success, saying, "My father wasn’t liking that so much."

He recalled, "In the middle of a game" his father began screaming at him from the stands, and then came onto the field. 

"I was going for a nearside backhand, and I didn’t do anything wrong — he goes, ‘You’re pulling too hard on the horse!’" he said.

"[Frank] comes out of the stands, grabs me by the throat, throws me on the ground, takes the horse, and walks off the field."

He added, "I laid there and I went, ‘I never want to see a horse again in my whole life.’"

Sylverster Stallone in a scene from "Sly"

Stallone recalled his father not "liking" that he was becoming successful at polo as a teenager, and ended up discouraging his interest in the sport.  (Netflix)

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Stallone later played again at age 40, and even invited his father to play with him in a game. But during the match, Frank Sr. hit Stallone in the back and he fell off the horse, which nearly trampled him. Stallone recalled, "He just rode away."

The actor added sadly, "That was it. I never played polo again from that moment on."

While pursuing acting in New York, Stallone also began writing his own screenplays and producing his own projects.

He wrote and starred in a silent Western-themed movie called "Horses," and had his father play a sheriff. 

As Stallone recalled, "The part where he kills us, he enjoyed a little too much," adding that he wondered, "Is this personal, sort of Biblical?"

Elsewhere, Frank Jr. described their father as "jealous."

Frank Stallone posing in a speedo with a dog

Frank Stallone, Sr. and dog Butkus on September 23, 1979 outside Sylvester Stallone's home in Malibu, California. Stallone and his brother both felt their father was jealous of the actor's success. (Ron Galella/Ron Galella Collection via Getty Images)

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After the success of "Rocky," director John Herzfeld said that Frank Sr. came to him with a script for a boxing movie. Herzfeld declined and encouraged him to speak with his son, but Frank Sr. refused.

"He was still competing with Sly," Herzfeld said.

Frank Jr. said the script was supposedly about Rocky’s son, and the two apparently spoke about it because he recalled Stallone saying, "You can’t do that dad, it’s my creation."

"I think my father was a little jealous," Frank Jr. continued. "I said, ‘What are you jealous of? He worked his ass off. You didn’t help him. He did this.’"

"Success can really wreak havoc on a family," he added, noting that his own career suffered in the shadow of Stallone’s. 

Sylvester Stallone seated with brother Frank Stallone Jr.

Frank Jr. admitted to his own career suffering in the shadow of his brother's in the documentary. (LGI Stock/Corbis/VCG via Getty Images)

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Friendship with Henry Winkler

Paul Mace, Sylvester Stallone, Henry Winkler, and Perry King pose for picture in a scene from the film 'The Lords Of Flatbush',

Paul Mace, Sylvester Stallone, Henry Winkler, and Perry King pose for picture in a scene from the film "The Lords Of Flatbush" in 1974. ( Columbia Pictures/Getty Images)

Stallone and Henry Winkler appeared together in the 1974 film "The Lords of Flatbush," and the pair formed an unexpected friendship.

After the film, Stallone drove to Hollywood where his car broke down and the first person he called was Winkler, who was starring on "Happy Days."

Winkler, in a spot on impression of Stallone, recalled the conversation, "Hey, you gotta come pick me up. My car broke down. I’m here, right in the middle of Sunset Boulevard."

"I went and got him, and this mountain of a dog, all of his clothes in the car somehow," the actor continued.

Stallone didn’t want to impose on his friend, so he stayed at a motel before finding an apartment that provided a surprise inspiration for "Rocky."

He ended up living "one street away from Balboa Boulevard."

Henry Winkler and Sylvester Stallone posing together

Winkler was the first person Stallone called when he arrived in Hollywood after his car broke down.  (David Keeler/Getty Images)

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Changes to "Rambo"

Sylvester Stallone as John Rambo

 Sylvester Stallone plays Rambo on the set of "First Blood" in 1982. According to Stallone, he made significant changes to the character.  (Sunset Boulevard/Corbis via Getty Images)

In the documentary, Stallone described the original version of his character John Rambo, the troubled Vietnam veteran, as "a homicidal maniac. He was a vicious casualty from the war. He came back broken. And [there was] nothing he could do to earn his way back into America’s good graces."

In preparation, the actor recalled, "I started really reading up on vets, and their actual words, situations, traumas" and took inspiration from their stories to include in the final film, adding, "you can’t make that s--- up."

Rambo was meant to die in the original version of the film, but Stallone objected after his research.

He remembered saying in a meeting, "I don’t want everyone who is a Vietnam vet to see this film and then me shot, and realize, ‘Oh so there’s no hope for me at all, none’" and then walking out. 

The test screening with the original ending went poorly, and they agreed to change it to Stallone’s revised idea.

"At that time, they were losing 20,000 vets to suicide a month. I don’t want to be part of that, I don’t. And I’m not going to," he added emphatically. 

Scene of Sylvester Stallone walking on the street in "Sly"

Stallone insisted on changing the ending of the original "First Blood" film out of respect for Vietnam veterans and their struggles.  (Netflix)

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Rivalry with Arnold Schwarzenegger

Sylvester Stallone in a blue suit looks unamused to his left (camera's right) split Arnold Schwarzenegger looks serious to his right (camera's left)

Schwarzengger said in the documentary that with "Rambo" Stallone had "stepped into my arena." (NBC/Phillip Faraone)

According to Schwarzenegger in the documentary, with "Rambo" Stallone had "stepped into my arena."

A rivalry began between the two stars in the '80s, with each trying to one up the other. 

"At that point we were like little kids. Who uses bigger knives? Who uses the biggest guns and holds them in one arm? … Who has more muscles? Who has more muscle definition? Who has less body fat? I mean, stupid stuff that we would be fighting over. Now we look back, and we laugh at the whole thing," Schwarzenegger said.

He added that he "was always trailing Sly," saying he couldn’t be stopped and that he was a "force in Hollywood."

As his star grew, Stallone tried to venture out of the action world and did comedies, including the critical and box office failure, "Stop! Or My Mom Will Shoot."

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Schwarzenegger claimed the film was offered to both of them, and Schwarzenegger turned it down, but the studio told Stallone the "Predator" star was interested, 

"Sly was going so nuts about the fact that I wanted to do it, and then he did the movie. And the rest is history."

Sylvester Stallone and Arnold Schwarzenegger pose at 'Creed' premiere in Westwood in 2015

Schwarzengger and Stallone's rivalry ended, and they even appeared together in "The Expendables" franchise.  (Todd Williamson)

Death of Sage

Sage Stallone with his father Sylvester Stallone

Stallone's son Sage made his film debut in 1990 in "Rocky V." He died at age 36 in 2012 from coronary artery disease.  (Ron Galella, Ltd./Ron Galella Collection via Getty Images)

Stallone’s only son Sage died in 2012 at the age 36 from coronary artery disease.

He had made his film debut in 1990 in "Rocky V" with Stallone.

Herzfeld says that Stallone wrote the film with Sage in mind for the part of Rocky's son: "He wanted to give him this opportunity that was so hard for Sly to get."

Stallone was asked whether he drew from personal experience in writing the strained father-son relationship in the film between his and his son’s characters, and he said, "Unfortunately, yes."

Sylvester Stallone and Sage Stallone in a scene from Rocky V

Stallone admitted that the relationship between father and son in "Rocky V" mirrored his own relationship with his son, Sage.  (John Bryson/Getty Images)

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He continued, explaining, "I try to take something that actually is what I wish I had done in real life, but I wasn’t able to do that in reality. And so quite often I would do it theatrically, magically."

He continued, "A lot of that [in "Rocky V"] is true. Unfortunately, you put things before your family. And the repercussions are quite radical and devastating."