A bored banker with a chronic bad attitude gets his life forced open by an unrelentingly affirmative self-help program. Imagine Frank Capra directing it with Jimmy Stewart in the lead, or Billy Wilder with Jack Lemmon, and the thing seems almost plausible as a classic comedy. But this adaptation of Danny Wallace’s book, by Jarrad Paul, Nicholas Stoller and Andrew Mogel for director Peyton Reed (Bring It On, The Break-Up), is content to remain a slightly above-average, just-admit-it’s-funny Jim Carrey vehicle. Carrey’s guru is Terence Stamp, fully game for lines like, “I want you to invite Yes into your lives, because it would RSVP ‘yes,’” and his love interest is Zooey Deschanel, fully game for lines like, “Life’s a playground; we knew it when we were kids.” Somehow Deschanel’s sweet-pixie-chick shtick actually mitigates Carrey’s dubiousness as a romantic lead. Of course, and appropriately, his restive humor will not be denied.