There are a few keys when it comes to deciding whether or not to become a police officer. First:Are you willing to put your life on the line? It doesn't matter what kind of officer you are you still have to be willing to do this.
Second

o you have decent pain tolerance? Just in training they
will pepper spray and taze you (At least in the US.)
Third: Can you fire a gun? (Kinda' obvious in its importance)
Fourth:Can you handle death...and gruesome ones. Officers have to see some messed up stuff on the job.
And Fifth and possibly most important:Are you willing to, and can you reconcile with yourself if you have to kill another human being. Hopefully it won't happen but there's a chance you'll be put in a situation where it's your life or someone else's life on the line and you will need to be able to pull that trigger and keep on going afterward. If the answer to any of those is no...you prolly shouldn't join the police