Run, Fatboy, Run (2008)

Synopsis
An overweight man leaves his fiancée on their wedding day, only to realize years later that she's the one and only woman of his dreams in a romantic comedy that reunites Big Nothing co-stars Simon Pegg and David Schwimmer. It's not easy to win back a woman after leaving her at the alter, but when an obese man finally realizes just what a mistake he made, he vows to run a high profile marathon in order to convince his ex-fiancée that the rich and handsome man she is about to marry isn't the guy for her. ~ Jason Buchanan, All Movie Guide