
Macdonald celebrated her 75th birthday this year by zip lining. “I have a tendency to do things that anyone else would say: ‘Oh my God! What’s she doing now?’” She has 1.4m followers and a partnership with the retailer Women’s Best. On Instagram, Macdonald posts photos of herself in sports tops, or jumping waves in beachwear. “Muscle is a tissue that can adapt with stimulus.” The key is to check with a doctor first, and start slowly. “There is a misconception that people over 65 cannot produce hypertrophy of the muscle,” says Mark Peterson, an associate professor of physical medicine and rehabilitation at the University of Michigan. “I’m going: ‘Wooh! That looks pretty good! I’ve got some muscles here.’” Within nine months, she was off all medication. “Wow! Your back!” people in the gym told her. She mimes raising a barbell and lowering it behind her head. She followed Michelle’s workout programme, using the machines, then light weights – 2.5lb (1kg) – working up to heavier ones. Macdonald learned to make protein shakes. She left her home in Ontario, Canada, to join Michelle and her husband, both fitness coaches, in Tulum, Mexico. I mean, she loves me, but you can love a person without even liking them.” She thought: “I want to earn Michelle’s respect. Macdonald’s thoughts swirled for two weeks. “I was sick and tired of being sick and tired.” “Of course I didn’t want it,” Macdonald says now.
