Only started thinking like this over the past 3 years now at 38.
But during my late 20's, early 30's I was in a comfortable job and I didn't care about pay. Now I care about pay!
That sounds like you're in the same position as me. I work with people on 15k more than me (different department) and they don't know how I can be happy with what I get, but I am / was lol.
I don't need or want expensive cars and nearly everything I buy is on offer or second hand, I just live within my means.
I wouldn't even go on holiday if it wasn't for my girlfriend or my daughter moaning at me to book something!
I'm not a work a holic but I definitely spend more time there than I should and don't get overtime etc.
Maybe I'll snap out of it soon but I've already started applying / looking for other jobs now.