For decades, personnel departments and managers have used the "Four Personality Types" to choose which individuals to hire or promote.

All four types (A, B, C, and D) were supposed to be useful to a well-rounded organization, but the overwhelming tendency is to treat it as a grading system, where Type A personalities are the winners and the other three types are the losers.

Hence, it's quite common to hear people brag about being "Type A" workaholic jerks while few willingly cop to being "Type D" people-pleasers who enjoy repetitive tasks.

I don't want to burst any bubbles, but the "Four Personality Types" are to psychology what horoscopes are to astronomy. Yeah, there's a patina of science, but the categories themselves are a pile of steaming truthiness.

I mention this because the original idea for this post was to identify which of the four personality types are best suited for Work-From-Home.

Unfortunately, the four personality types were conceived long before the advent of the internet and the hundreds of online tools that we now have available to coordinate work efforts remotely.

Because the four personality types assume everyone is working together at an office or manufacturing facility, they simply don't apply to a world where virtual reality threatens to make centralized offices themselves entirely obsolete.

Thus, we'll need to look elsewhere to find guidance about the type of personality who should be working from home.

As it happens, I'm an extreme case of somebody who's well-suited to working from home. For example, I co-authored a book with a person who lives an hour south of where I live and work. We did the entire project without ever meeting in person. I could cite dozens of other examples, since I've never met most of my editors and clients face-to-face.

Furthermore, since I've been working from home for over two decades, I've been asked "what's your secret?" by at least a dozen people who want to go freelance. In the process of informally coaching them, I've learned what type of person doesn't do that well at this.

With that in mind, here are the five characteristics of people who can be highly successful working from home:

1. They're Introverted

I've repeatedly explained that introverts are peculiarly ill-suited for today's open-plan offices, while extroverts tend to like the extra stimulation. The obverse is true as well: Introverts adapt to working from home much easier than extroverts.

Back when I worked in cubicle-land, I worked with a guy whose job was to attend meetings of other groups and report back to our group's management to make certain that those other groups weren't intruding on our turf. (Yes, that's a real job.)

Now, for me, that job would be the seventh circle of hell, but this guy enjoyed it. Anyway, after he got laid off, he tried doing freelance marketing and, since I'd been doing that for a while, I gave him some pointers.

He tried his best to make it work but got so lonely that he took the first job he could...and ended up with a job much like that he had before, but for an even larger company. He was happy as punch.

2. They're Self-Disciplined

In the workplace, there are two huge sources of external motivation: 1) peer pressure from people who'll glare at you and resent it if they notice you're goofing off, and 2) the likelihood that your boss will "go walkies" and look over your shoulder to confirm that you're working.

Neither of those are present when you're working from home, which means that you've got to get your own *ss in gear every day and get your work done...even though nobody will notice if you play video games for a few hours.

Food is another temptation. A guy I used to work for (and ran into at the local gym) put on 20 pounds in first six months he worked from home. Fortunately, he had the discipline to change his behaviors; otherwise he would by now be seriously obese.

3. They're Not Paranoid

The Harvard Business Review recently published a study of 1,153 office workers, 53 percent of whom worked from home at least some of the time. It revealed that:

Remote employees are more likely to report feeling that colleagues mistreat them and leave them out. Specifically, they worry that co-workers say bad things behind their backs, make changes to projects without telling them in advance, lobby against them, and don't fight for their priorities.

What's interesting about the study is that it didn't probe to see whether these worries were justified. To my mind, worrying about this sort of thing is more than a little paranoid. Chances are, your co-workers are just trying to get their own jobs you'd realize if you were back at the office.

I learned early on, while working from home, to suppress whatever paranoia I possessed. The only time I remember feeling paranoid recently was when a carpenter, who was hammering boards onto my deck, called me "a paranoid weirdo" Morse code.

4. They're Technically Competent

Most offices have an IT expert or group who can diagnose and fix day-to-day problems with whatever computer setup you're using. While working with "the guys from IT " is frequently a pain in the butt, their presence frees you from worrying much about technical trivia.

When you work from home, however, you're pretty much on your own. If your computer acts up and you don't possess at least a modicum of technical ability, you'll be spending many unproductive hours on the phone with customer service.

Hint: Supporting a Macintosh requires 1/100th as much effort as supporting a Windows machine. If you're working from home and using Windows rather than a Mac, you may be technically competent but you're incompetent when it comes to doing a cost-benefit analysis.

5. They Know How to Sell

Finally, and most importantly, people who work from home must continually sell their services to their employers or clients. Realizing the truth of "out of sight, out of mind" isn't paranoia but simply a recognition of how humans think and behave.

When you work in an office, you're selling implicitly by showing up and looking busy. That's not the case when you work from home, so that means more status reports and updates and a willingness to "jump to it" when your boss makes a request.