Use the “show do not tell” rule to describe: She was getting old.
“Where are my glasses?!” she muttered.
“On your nose.”
She smoothly passed her hand through her hair. It was an all too familiar gesture for me; she always did it when something was on her mind. I loved to watch her gently pull out a single hair, wrapping it and unwrapping it around her finger like a child fiddling with his fingers.
This time, the hair was white.