Kevin's Watch

A cute British film. A loser who leaves his pregnant bride at the altar spends the next 5 years being a part-time Dad and trying to get her back. Her new boyfriend is a marathon runner, so Dennis decides to run just to compete with him.

Just enough foulmouthed Brit humor to be genuinely funny and not gratuitous.

www.imdb.com/title/tt0425413/

If you liked Fatboy, try Hot Fuzz (as long as you're ok with comedic violence)

....And Shaun of the Dead

Simon Pegg is a comedy genius, not to mention an excellent Scotty in Star Trek. ( His wife is Scottish, which explains his accent as Scotty).

A comedy set in London. Simon Pegg as Dennis may not have been the director's first choice, but he's not bad as a very nervous groom who runs out on his pregnant wife Libby (Thandie Newton) and five years later comes to deeply regret it. Libby gets involved with successful American businessman Whit (Hank Azaria) who is a narcissist on a power trip, and Dennis hates him and wants to win Libby back from him. Whit challenges Dennis to enter a 26-mile running marathon, and Dennis accepts to prove he can have discipline and perseverance, qualities Whit states Dennis lacks. The comedy mostly falls flat, but has its moments. Each marathon runner must represent a charity, printed on their running shirt, but the only charity interested in Dennis is the National Erectile Dysfunctional Awareness. Kind of funny, as is the scene where Dennis has his cousin Gordon (Dylan Moran) pop a giant blister on the sole of his foot. But, it is not funny enough, and the movie's not serious enough to be a satisfying drama, either. The story is rather predictable, on the whole. I kind of like Dennis and the characters who help him train for the big race, and Pegg, Newton, and Azaria show some acting chops in this one. But don't bother with this. I wouldn't run from watching this movie, but I would stroll briskly past it, I think.