Amid the overwhelmingly positive critical, fan and box office success of "Guardians of the Galaxy Vol. 2," director James Gunn has opened up about the loneliness and personal struggles that led him to the superhero genre in the first place.

The Missouri-born director was relatively unknown before he signed on to direct 2014's "Guardians of Galaxy," a film about a ragtag bunch of obscure space-faring Marvel characters. But after the smash-hit success of the first film, and following on the heels of a US$145M opening weekend for the sequel, Gunn and "Guardians" have become a major success story in Hollywood.

In his that has since gone viral, Gunn admitted that he's been keeping a close eye on the box office success of "Guardians of the Galaxy Vol. 2," which earned 54 per cent more in its opening weekend than the original film. "But in the end, it's not what matters to me," he wrote in the post. "I'd like to remember that that's all truly nonsense and noise."

Gunn explained that he makes movies not for the money, but because he sees filmmaking as a way to connect with others who feel strange or isolated, like he did when he was young. "I do it so that some kid in Thailand, or England, or Colombia, or Brazil or Japan, or Russia, or anywhere, can hear the frequency of his or her own heart bouncing back off the Guardians," he wrote. "They're a group of heartbroken misfits whose lives have been bereft of tenderness and connection and who have a nearly impossible time trusting themselves or others. But they're learning, one step at a time."

Like his characters, Gunn said he often felt "utterly alone" when he was growing up in suburban Missouri, to the point where he entertained dark thoughts and felt unable to connect with others. "But I found my respite in popular entertainment," Gunn said, citing influences such as the Sex Pistols and Marvel Comics. "Suddenly I could see past the bland suburbs where I lived to a more magical world, a world more aligned with what I imagined."

The 47-year-old says little things like Freddie Mercury lyrics, David Cronenberg films or "Chewbacca's growl" were enough to shake him out of his sadness, and helped him realize that "I wasn't completely alone. Someone out there was as weird and strange and whacked out as I was."

He said the oddball characters in "Guardians of the Galaxy" are his way of reaching out to those who feel like he once did. "They are me. They are you. We are Groot," he wrote. "And no matter how much world leaders are telling you we aren't in this together, we are. You are not alone."

Gunn finished the post by confirming that he will spend the next three years developing a third "Guardians" film.

"Thank you so much, Facebook friends, for supporting me over the past two and a half years," he wrote. "And thank you for all the messages letting us know we've keyed into the frequency of your hearts."