Mark Ruffalo visited the event to promote Oscar-nominated movie "The Kids Are All Right", in which he plays a sperm donor dad, and it was enough to make him rethink his plans to give up acting.
The actor had fired his assistant, agent and publicist after making the film and moved his family to Callicoon, New York in the hope of finding a new career to satisfy him.
He tells Details magazine, "I'd had it with L.A. and I really had it with the business side of acting, the machinery of it all. You're an artist, but then all of a sudden you're a product at the same time, and there's this company that's sprung up around you.
"I got depressed. I was losing my love for it. So I said, 'I'm done'. I fired everybody and moved my family out here. I had to make a radical move.
" 'The Kids Are All Right' was my swan song. I didn't know what I was doing next."
But he agreed to promote the film at Sundance in Utah, and the experience gave him a new desire to act and make movies.
He adds, "Watching everyone's jaded, supercool Hollywood identities melt into the communal experience of filmmaking and storytelling, it reminded me, 'I'm an actor, and my whole life has been geared towards being an actor'."