There is nothing to commend Run Fatboy Run even the theme that true love will triumph. Dennis Doyle is a pathetic loser who runs away from the wedding to the mother of their child. He does keep in contact with their son and it is this contact that makes him realise what he has lost when she starts to date someone else. The man is an investment banker who is running in the London Marathon. This spurs Denis to enter and train and to finisher higher that the rival. For some reason this makes his former fiancée think better of him and they get together again. God help her and her son I say.