I was doing my MSc part-time (UK) and working to pay for it (worked 4 days a week, MSc 2).
I worked in a cafe in a library. Thought it'd be a cushty job, cos it's a library. I was SO wrong. There was tonnes wrong with this place but one was a major shortage of staff. They just refused to hire enough people but also refused to serve a realistic food menu.
One day I was scheduled to close (6:30pm). I had acute tonsillitis (first time ever) and was completely delirious with a v high fever. Told them I needed to go to the GP for antibiotics. They said “OK but you need to come back to close afterwards”. The doctors was a two mile walk away and it was snowing but I went back.
Sat down for the last hour (again, I was delirious with a v high fever) and the manager came over and told me to stand!
It was then I decided I'd never do another customer facing job and I never have. I'm half way through my PhD and its hard but its miles better than that bs.