Happy Birthday, br John Mayer!.br John Clayton Mayer turns br 46 years old today.br Here are five things you may not have known about the singer.br 1. Mayer was inspired to br play guitar after watching br Michael J. Fox’s guitar solo br in ‘Back to the Future.’.br 2. He once broke his Grammy award for br Song of the Year in half to split with Alicia Keys.br 3. Mayer has a watch br collection worth br millions of dollars.br 4. After he was diagnosed br with cardiac dysrhythmia br and spent time in the hospital, br he began writing songs.br 5. He has an “SRV” tattoo in honor of late guitarist Stevie Ray Vaughan.