There are few times inside a business that can be more difficult or unpleasant than firing someone -- it's not fun for either party. However, terminating employment is an important part of success as keeping someone on the team that is not a good fit can be incredibly detrimental for both the company and the individual.

The worst-case and most difficult to detect scenarios is when you have an employee, whether part of the office or sales team, that is still performing well but is losing interest in his or her position or the company. The person is mentally "checked out'." This presents an enormous risk to your business as these types of people and their attitudes spread like a virus through your staff, infecting everyone else as time passes.

Think you have someone that would rather be anywhere else besides in front of his desk? Here is how to handle the situation.

Related: How to Let Go of Employees With Love and Dignity

Pay attention to the signs. There are a couple of obvious (and not so obvious) signals that you should pay attention to that will help you understand when an employee's mind is headed out the door.

You will typically see slight changes in attitude, dependability, preparation and timeliness. Have you noticed that someone that historically stuck around to contribute and is now doing everything they can to be the first one to leave a meeting or the office at the end of the day? Or someone that was once deemed a team player who now prefers not to be disturbed? If so, you’re dealing with a pretty substantial change in attitude that you need to pay attention to.

These issues don't necessarily happen all at once, but they're all signs that there is an problem building. It is important that you address these issues immediately, directly and in person.

Act quickly. Unfortunately, it is almost impossible to turn someone around that is mentally checking out. It doesn't mean it can't be done or you shouldn’t try, but it's pretty unlikely.

When it becomes clear that they can’t be revived, you need to make the move immediately. I suggest acting within five business days or less. This point must be reiterated -- the longer you wait to address your concerns, the worse the situation is going to get. There should be no exceptions to this rule, as this individual has personal relationships with your other staff members, which could lead to a much higher probability that they will begin to poison your remaining team.

Related: How Hiring and Firing Employees Is Just Like Poker

Help them learn. When you’ve made your decision and it comes time to release the employee, try to do so within a day or two. Also opt for an early morning meeting, a time well before other staff members come into the office. By doing so, you avoid others witnessing a possible scene as well as the person having to do the "I just got fired" walk of shame in front of everyone.

Keep in mind their failure is not because they're a bad person -- they are just not a good fit for the company or the company is not a good fit for them. Keeping them in a position at a company that they aren’t a good fit for is not any better for them than it is for you.

This is your opportunity to be a leader and give them the chance to learn why they are being released, so they can make personal improvements moving forward. Remember, this is a traumatic event, even if it's not exactly a surprise. Be calm, kind, honest and engaging as you deliver your decision.

Related: How to Fire Yourself With Grace When It's Time to Take Your Company to the Next Level