You've been protecting the public your entire career. Now you can apply those skills to serving one particular VIP or company. Security guards protect their clients against theft, vandalism and other illegal activities.
As a security guard, you may patrol one specific area, such as a mall parking lot or bank entrance. You may just guard an entrance -- like at a military base or museum -- to make sure that everyone who enters is supposed to be there, and that visitors don't carry in any dangerous materials. If you're a bodyguard, you may protect a public figure, like a celebrity or politician, from harm or just keep away autograph seekers.
As a security guard, you're going to spend much of your time watching for events that don't happen. But if you're put in a situation where someone threatens the place or person you're protecting, you might find yourself in the same kind of armed conflict you could have experienced while on the police force.
In most states, you've got to be licensed and pass a background check to work in private security. Many security guards carry a gun -- for which you'll also need a license if you don't have one already.