Bank loan officer Carl Allen has become withdrawn since his divorce from his wife Stephanie. Having an increasingly negative outlook and ignoring his friends Peter and Rooney, he misses Peter and his fiancée Lucy's engagement party. His old colleague Nick suggests that Carl attend a motivational seminar that encourages people to seize every opportunity to say "yes". At the seminar, Carl meets inspirational
guru Terrence, who has him enter a "
covenant with the universe" and say yes to everything asked of him. As they leave the seminar, Carl says "yes" to a homeless man's request and becomes stranded, out of gas, and with no battery life on his cell phone in
Elysian Park. Walking to a gas station, he meets Allison, an eccentric young woman. She gives him a hectic ride back to his car on her scooter and, when he asks her to make out with him, she kisses him before leaving. A few days later, he is offered oral sex by his elderly neighbour Tillie for helping her put up shelves; when he declines and immediately experiences bad luck, he returns and surprisingly enjoys the moment. After having a pleasant workday, Carl is convinced that he must continue to say yes, as his previous misery was the consequence of refusing opportunities. He renews his friendships with Peter and Rooney; builds a bond with his nerdy boss, Norman; assists Lucy with her bridal shower; and learns to speak Korean, play the guitar, and fly airplanes. Accepting a band flyer outside of a coffee shop, Carl sees an idiosyncratic band called Munchausen by Proxy; the lead singer is Allison. He is charmed by her quirkiness; she is delighted by his spontaneity, and they begin dating. They sneak into the
Hollywood Bowl and sing "
Can't Buy Me Love" by
The Beatles, among getting up to other hijinks together. Carl earns a promotion at work after approving several microloans and, using his guitar lessons, plays
Third Eye Blind's song "
Jumper" to persuade a man not to commit suicide. Carl and Allison meet at the airport for a spontaneous weekend excursion. Having decided to take the first plane out of town, regardless of its destination, they end up in
Lincoln, Nebraska, where they bond more. Allison confesses her love for Carl and asks him to move in with her, and he hesitantly agrees. While checking in for the return flight, Carl and Allison are detained by
FBI agents who, due to Carl's recent erratic behaviour, have profiled him as a potential terrorist. Peter travels to Nebraska as Carl's attorney and explains the situation of Carl's responding to every request and opportunity with yes, simultaneously revealing the truth to Allison. Deciding she cannot trust him, she leaves Carl and refuses to return his phone calls. Having almost forgotten about Lucy's shower, Carl quickly arranges a major surprise party, as well as setting up Norman and Rooney with Soo-Mi and Tillie, respectively. After the party, Carl receives a tearful phone call from Stephanie, whose new boyfriend has walked out on her. When he goes to comfort her, she kisses him, asking him to spend the night. After Carl says no, his luck takes a turn for the worse. Deciding to end the covenant, Carl returns to the convention centre and hides in the backseat of Terrence's convertible so he can be released. However, he pops up while Terrence is driving, startling him and causing a collision. Once Carl regains consciousness in the hospital, Terrence tells him the covenant was merely a starting point to open Carl's mind to other possibilities, not to permanently take away his ability to say no. Freed from this restraint, Carl finds Allison teaching her sports-photography class and admits that he is not ready to move in with her yet but genuinely loves her, and they reconcile. Carl persuades the attendees of Terrence's next seminar to donate the clothes off their backs to charity, so Terrence is greeted by an entirely nude convention centre. ==Cast==