Getting old

Getting old
 

¿Còmo se dice?

I know I'm getting old when I see pictures of people that I went to school with and think "they look old!" (When I say old I don't mean like a really old person but not really young)

Se que me estoy haciendo mayor cuando veo fotos de personas con quienes fui al colegio y pienso "ellos se van bastante mayor".

I wasn't sure about this translation as I'm taking about people in their thirties???

There's a verb for to grow old in Spanish. It's envejecer. You can wrote something like:
Sé que estoy envejeciendo cuando veo mis socios de colegio y se ven bastante mayor.