(CNN) - It was only a year and a half ago that a phenomenon swept the globe and made basketball fans a little, well, "Linsane."

Remember that? Back then, Jeremy Lin led a historic New York Knicks winning streak, dubbed "Linsanity." Crowds fell for the feel-good story of an overlooked bench-warmer who slept on friends' sofas to take a shot in the NBA.

A new documentary takes a look at the life of Jeremy Lin before the madness.

"Linsanity," out in select theaters October 4, offers a glimpse of Lin's road to stardom: He was a standout basketball player in summer leagues, competed in a tightly contested high school state championship and faced racial epithets as an Ivy League athlete before landing, undrafted, in the professional league.

From the documentary, it's clear the 25-year-old Lin was used to being an underdog, and overcame his share of challenges with a deep faith and persistent spirit.

"I'm always trying to have a good time, joking around, goofy," he said. "I think I try not to take anything really too seriously."