Remember the slacker Pegg hilariously played in Shaun of the Dead? Dennis Doyle is just as much of a loser. But instead of fighting zombies Dennis’ engaged in a battle of the bulge. Five years after leaving a pregnant Libby (Thandie Newton) at the altar Dennis is out of shape out of money and out of his ex-fiancée’s good graces. Libby’s now dating Whit (Hank Azaria) an American businessman who’s everything Dennis isn’t. “He’s handsome well-off friendly ” we’re told several times. Threatened by Whit’s presence in the lives of Libby and son Jake (Matthew Fenton) Dennis finally gets his butt out of bed when he decides to compete against Whit in a charity marathon. Dennis can barely sprint to the bus stop and back and he’s only got a month to get fit. But he’s convinced running the marathon will allow him to win back Libby and make him look like a hero in Jake’s eyes. And so Dennis makes like every underdog we’ve come to know and love in his bid to drop the extra pounds run the marathon and recapture Libby’s heart. Too bad this takes him--and Run Fat Boy Run--down the marathon route well traveled. Shaun of the Dead and Hot Fuzz proved that Pegg’s damn funny whenever he’s spoofing all things Hollywood with director Edgar Wright. Unfortunately he doesn’t have what it takes to be the next Hugh Grant. Pegg’s mastered the art of slothfulness but he’s ill at ease trying to express genuine emotions or generate some sparks with Newton. Maybe his discomfort stems from the padding he wears around his waist. Still there’s some tenderness to be found in the interaction between Pegg and the affable Fenton. If Schwimmer wanted to distance himself from Friends’ nerdy Ross he should have cast himself as Whit. The problem with Azaria--who looks even more ripped than he did in Along Came Polly--is that he reveals just enough of a hint of insincerity when we first meet Whit to tips us off that will become the “arsehole” Dennis thinks he is from the start. Newton sadly doesn’t have much to do other than to look through Pegg and gaze longingly at Azaria. But Irish comic Dylan Moran as Libby’s scheming cousin and Jake’s pal pretty much runs away with Run Fat Boy Run with his biting wit devil-may-care attitude and frequent flashes of flesh. So Schwimmer’s the latest sitcom star to go all Rob Reiner on us. OK he did try directing during his Friends years. Luckily Run Fat Boy Run represents a significant improvement over 1998’s consigned-to-TV Since You’re Been Gone. Schwimmer keeps things light and breezy but he’s saddled with an uneven script by his Big Nothing co-star Pegg and The State’s Michael Ian Black. Things start off quite flat and unfunny but the film gains much comic impetus when Dennis begins training in earnest. Some of Schwimmer’s directorial touches do seem somewhat gimmicky. Do we really need to see Dennis attempt to crash through an imaginary brick wall when he runs out of energy miles from the marathon finish line? Still Schwimmer does good job of involving us in Dennis’ plight even if the outcome is never in doubt. Unfortunately Pegg and Black never strive to surprise us. How refreshing it would be to discover that Whit is the right man for Libby forcing her to choose between both suitors. But everything you suspect will happen does happen right down to the film’s Rocky-esque ending. Unfortunately like Dennis himself Run Fat Boy Run never tries hard enough until it’s do-or-die time.