Before getting hired for any department or agency you will go through a very thorough background investigation. At this point, they will talk with schools, friends, family, bosses, co-workers, to find out who you are and how you operate.
If hired, you will have to attend a training academy. These tend to be kind of militaristic, in their operations.
Once on the job not only is it important to have good attendance for the job, but also on calls.