In my mid 30's I didn't think I could make it 30 years. While this job does wear you down, surprisingly, it also keeps you in shape. I'm now over 50 and can count on one hand how many years I have left to get to the 30 year mark. With the route I'm on, I may choose to stay several more years in order to reduce my debt more before retirement.
Slow down, pace yourself. Years ago, my local BA told me to put a penny in my shoe whenever a sup rode with me. The penny would remind me of my pace at every step. If the sup said to speed up, my response would be "this is my 30 year pace".