Well... B'sides the 12 hour days/nights there's the frequent PTSD inducing incidents..
Y'know.. Suicides attempts, physical assaults, medical emergencies, over-doses, death threats...
Ever been bitten by a Hep-C or HIV positive crack whore...?
Then there's the strong likely hood you'll get suspended or fired over pretty much any incident where you use force to defend yourself or others.
Add to that the reams of paperwork involved and the Monday morning quarter backing done by people who have never actually done your job, but their book tells them how.
It's a wild ride and getting worse and worse as the years go by... Thank goodness I'm out shortly... Then I'll sit back and collect that huge public sector pension everyone seems to resent...
'Prolly buy a GS1250 with part of my severance...
I recall my prof in Police Foundations (30+ years retired inspector IIRC) telling me her first shift was a suicide at Spadina subway station. Grey matter everywhere. Not my cup of tea.
EDIT: Forgot, i did security for awhile, some shifts in the not so nice areas of town. I've had my fair share of heads knocked, running away as fast as possible and EMS being called for me. Hit 30 and said F this.