I was a fireman, retired. 24 hour shifts, worked a day off a day for 3 days and then off 4
Nurse in a women's prison now, work a week, off a week.
Firefighter - civil service testing. Big city be easier, lot more people testing though. Small cities and towns usually want you with state certified training, and paramedic training. So you save them money and go right to work.
Nursing - well, 2 years minimum college unless you have some of the general stuff out of the way.
I went to nursing school while working FT at the FD with trades and my days off. Got my bachelors after I retired.
Nobodies asked, how old are you and what do you do now?