Okay, so I'll share my professional situation first. I've been working at this school for over 12 years. Yes, I'm flexible to help out if it's needed (and I don't have other things planned), just like my bosses help me out if something happens. Some give and take is perfectly fine imo, as long as there it goes both ways.
However – would my bosses expect me to work an extra hour once a week and it isn't something temporary, I would obviously demand that my hours would be cut from my schedule at another time.
Personally, I wouldn't ask for extra pay since I've come to a place in life where the amount of money I can earn isn't my main incentive – mental health and a healthy work-life balance is way more important.
As for working super hard, aka above and beyond… I'm professional and I do my job, but I wouldn't sacrifice my physical and mental health (again). I also wouldn't work for multiple people just because they are too cheap to hire an adequate number of people. And let's say they aren't staffed enough due to financial hardship – unfortunate, but not a reason for anyone to jeopardize their health. Staffing is the employer's job and they usually get handsomely paid for it.
At the end of the day, I work to live, not the other way around.
My question is – what's wrong with this mentality?