Diary of a Wimpy Kid: The Last Straw (Book 3), Jeff Kinney

Greg Heffley's dad is on a mission! He's decided it's time for this wimpy kid to become, well, less wimpy and has planned lots of "manly" activities for him and his son. Greg somehow manages to find ways to get out of most of them, but when his dad threatens to send him to a military academy, Greg realises he's going to have to somehow shape up ... or get shipped out!