I think the actual playing wasn't the issue. Joe and his wife have two young kids. With the extra time that England training camps, tours, international games, etc all take up, he and all the other England players likely have about 4 weeks in a year where they're not training/rehabbing/away for days/weeks at a time. It takes a mental as well as physical toll on people. He most likely feels that he's missing out on important times with his young family that are far beyond measure & even unconsciously he sees the time & effort of international duty that takes him away from his family is to blame.