DEAR MAYO CLINIC: My grandmother lives with me, and she is always nagging me to “stand up straight” and “put your shoulders back.” She says good posture will keep me healthy as I age. But I’m only 17.

DEAR MAYO CLINIC: My grandmother lives with me, and she is always nagging me to "stand up straight" and "put your shoulders back." She says good posture will keep me healthy as I age. But I'm only 17.

DEAR MAYO CLINIC: My grandmother lives with me, and she is always nagging me to “stand up straight” and “put your shoulders back.” She says good posture will keep me healthy as I age. But I’m only 17.

As a child, being told to sit or stand up straight may have felt like a nuisance, but those adults in your life were on to something: Good posture helps you stay healthy and pain-free. “It can affect ...