Source: Bang Showbiz NewsSimon Cowell has hired a personal trainer to work with him three times a week.Simon Cowell has hired a personal trainer.The music mogul is working with a fitness guru to get him sweating in the gym and help him cut down on smoking, drinking and eating sweet treats.Simon has been working out at his own gym at his Los Angeles home while he films 'The X Factor' USA and so far things seem to be working out.He posted on his twitter account: "I now have a trainer three times a week. Feel so much better ... That's a fitness trainer."The 53-year-old star recently started dating model Louise Griffiths - who is 19 years his junior - and it has been claimed he has started the new exercise regime to get fit for her.A source told the Daily Star newspaper: "He's doing everything he can to look good. It's no secret that he's a bit vain, and he knows he's got to work hard to stay in shape."British beauty Louise was set to marry Formula 1 racing driver Jenson Button in 2005 but the pair broke off their engagement just months before their wedding day.Although her and Simon's relationship is still in the early stages they are believed to already be "very close".A source revealed: "She and Simon have started to get very close. It is early days but there is certainly a chemistry between them."Simon was recently romantically linked to Carmen Electra.He got engaged to make-up artist Mezhgan Hussainy in 2010 but they split a year later, and his other previous girlfriends include Sinitta and Terri Seymour.