A personal trainer says everyone over 40 should be doing this 15-minute workout to keep their bones strong

A woman exercises at home. She's holding dumbbells overhead while standing; behind her are green plants and shoes. .

If you’re worried about becoming frail in your later years, you need to start building bone strength decades in advance.

“Around the age of 40, our natural bone remodeling process shifts,” explains Mark Harris, a certified strength and conditioning coach and ambassador for strength training equipment brand Mirafit.