NEW YORK (AP) — Joan MacDonald’s health was in shambles at age 71. She was overweight and on numerous medications with high cholesterol, rising blood pressure and kidney trouble. Her daughter, a fitness coach, warned that she’d wind up an invalid if she didn’t turn things around. She did, hitting the gym for the first time and learning to balance her diet with the help of a brand new tool, an iPhone. Now 75, she’s a hype beast for health with a bodybuilder’s physique and 1.4 million loyal followers on Instagram. MacDonald is among a growing number of “grandfluencers,” folks 70 and up who have amassed substantial followings on social media with the help of decades-younger fans.