Simon Pegg (Shaun of the Dead, Hot Fuzz) stars as Dennis Doyle, a young Londoner who, in a fit of panic, ditches his pregnant girlfriend Libby (Thandie Newton) on their wedding day. Several years pass by and Dennis realizes what a horrible mistake he's made. Libby is now dating a "perfect" American named Whit (Hank Azaria), who is everything Dennis is not: fit, successful, rich, and charming.

By all accounts, Dennis is a loving father to his son, but it dawns on him that he has not been a particularly good person. His feelings for Libby remain strong and he yearns for another chance at her love, or at least some respect and an opportunity to apologize. To accomplish this, he follows Whit's lead and signs up to run a charity marathon. Dennis would seem an unlikely candidate for a run, given his physical condition. ("I'm not fat; I'm unfit!" he tells someone.) But his best friend Gordon (Dylan Moran) and Indian landlord Mr. Goshdashidar (Harish Patel) agree to be his trainers. They find that whipping him into shape is even harder than they think it will be but, fueled by a desire to show Libby that he's capable of change, Dennis perseveres.

Over the years, we've seen a lot of inspirational sports-themed movies, and we've seen even more parodies of inspirational sports-themed movies. Run Fatboy Run is neither of them. Although this is certainly the story of a man trying to prove his worth via a grueling physical challenge, the film avoids the kind of grandstanding that many pictures use to sanctify their heroes. In other words, Dennis is not some larger than life hero; he's a simple-yet-flawed guy with something to prove. And while the movie does have its share of funny training montages, the point is not to ridicule Dennis but rather to show what he has to go through in order to whip his flabby body into something resembling shape.

Amazingly, the picture manages to juggle both the silly and the sentimental without falling flat. Consider the two best scenes in the film. In one, Dennis develops an enormous blister on the bottom of his foot from running. This leads to a sublime grossout joke as Gordon tries to help him drain the fluid from it. It's a disgustingly hilarious moment. Later, there's a scene set on the balcony of a high-rise, in which Dennis explains to Libby why he ran away. Their conversation is genuinely touching. Trying to mix outrageous laughs with heart is not easy; the risk of tipping too far in one direction or another has ruined many a film. However, director David Schwimmer (yes, that David Schwimmer) stands firmly on the center of the see-saw, keeping the story's balance just right, allowing its disparate elements to pleasantly co-exist.

Much credit must also go to the performers, especially Simon Pegg, who again proves himself a master of physical comedy. Pegg knows how to do a pratfall that doesn't feel like an obvious gag. He also delivers his dialogue with sharp comic efficiency, never belaboring a joke but always finding the reality in it. Check out the scene in which he and Whit share a locker room to see what I mean. I also liked Thandie Newton, with whom Pegg generates some real sparks. Sometimes in romantic comedies, the chemistry between the lead actor and actress feels forced. This time, it seems like the two stars genuinely enjoy playing off one another, which only makes us believe even more that Dennis and Libby may still have feelings for one another.

One of the things I appreciated most about Run Fatboy Run was how the screenplay (by Michael Ian Black and Simon Pegg) handled the big race, which is, of course, a showdown between Dennis and Whit. I was expecting the usual clichéd scenario, but got something much more satisfying, honest, and real. I won't give it away, except to say that you can actually believe how the race plays itself out for the most part.

Admittedly, a few things here are clichéd. In any movie like this, the "perfect" guy usually reveals himself to be anything but perfect. The plot also pulls one or two manipulative strings in its final act. No biggie, though. I laughed quite a lot at Run Fatboy Run and, just as importantly, I felt myself rooting for this out-of-shape slacker to prove his worth. Not to Libby so much, but to himself.

( out of four)

DVD Features:

Run Fatboy Run comes to DVD and Blu-Ray on Sept. 23 with both widescreen and fullscreen formats on the same disc. (Do I even need to tell you to pick the widescreen?)

The discs contain some strong bonus features starting off with fourteen deleted scenes (with optional director commentary). Most of them are tiny trims from the story's final act, excised to keep the pace brisk. Nevertheless, once you've seen the finished cut, it's fun to go back and see some of the tiny little details that were lost.

Next up is a blooper reel that is routine, save for Simon Pegg's tendency to crack up, which is contagious. Pegg, like Ricky Gervais, is one of those people who make you laugh simply because he's laughing.

And laugh he does on the best bonus feature: a practical joke played on him by Thandie Newton. During a press interview to promote the movie, Pegg discovers that the water in all his bottles has been replaced with vodka. Watching his reaction as he goes through one bottle after another is hilarious.

Additionally included are two versions of the theatrical trailer: a domestic version and an international version.

Last, but certainly not least, is the feature-length audio commentary from Schwimmer, Newton, Pegg, and Pegg's mother, who chimes in occasionally from the background. (Now there's something I don't think I've seen on a DVD before - commentary from the star's mom!) The main participants share an easy chemistry; it is clear from the commentary that they all got along well during production and are proud of the end result.

Run Fatboy Run is the kind of movie that's fun to curl up with on DVD when you're in the mood for some light fun. It's got a decent number of laughs, as well a story that pays off on a feel-good level.

Run Fatboy Run is rated PG-13 for some rude and sexual behavior, nudity, language and smoking. The running time is 1 hour and 40 minutes.