Eeyore,
Sadly,I know what you're talking about.My stamina is good,though...but after hour 13 of a 16 hour day,I do get a little worn down.It's not as easy as it was in my 20's!
I sit when I get into my car to drive home.
I know what it's like to do 35 hours in three days and work 49 days in a row without a day off.You're right that there is little tolerance in this profession for wanting a life outside of work,but that is part of the job.You either accept it or move on.A friend of mine is a sous for Ritz-Carlton and his father died.They called him after two days and asked him to come back in because they needed him.That's just the way it is.It isn't always fair,but neither is life!
At my job,we have a woman [I'm not being sexist;I'm a woman,too] who is always whining about how this hurts,that hurts,etc.Well,as good as she can be when she's fresh,she is a drain on the team when she's in one of her moods.We will literally just send her home because she kills the morale with her daily complaints of problems.We all hurt some days,but keep it to ourselves.
She's gotten to the point where the next time she tries to leave early or call out because of whatever ails her,she's going to be demoted to "on-call" status,lose her benefits and whatever status she held in the kitchen for the past 5 years.It's nothing personal,but if she can't hack the job,we have to find someone who can or divide responsibility among others on the team.It's a business.
I know you stated you do not call out sick and you do your job,but this is just an example.
For the most part,whoever is in charge could care less what your problems are;they want the job done because being down a person can really mess up the flow of the kitchen and they are looking at the bottom line.
This is a feast or famine business;either you're struggling for hours or you live at where you work.This is a profession of extremes.I think it's better for you to realize your limitations if you have health issues than to force yourself to do something you know you can't.Sometimes things like that can haunt you later if you have inadvertently developed a reputation for not being able to keep up....because the truth of this industry is everyone is expendable to some extent.