To many employers, the Millennials (aka: Gen Y) entering our professional work environments are a mystery. And research shows they are certainly a unique generation whose members have no trouble telling employers what they want, and need, to be happy at work.

But why are companies, large and small, spending so much time worrying about how to retain this generation? Why are some well-known companies completely overhauling their cultures to better accommodate this generation? It's basically a matter of math. Based on research released by the Employment Policy Foundation outlining demographic shifts affecting population trends in the U.S., our country is at the beginning of a labor shortage of approximately 35 million skilled and educated workers, starting now and estimated to continue over the next two decades. And, according to a report released by the U.S. Bureau of Labor Statistics, starting this year, the labor shortage will begin to affect U.S. corporations and small to medium-size businesses to the tune of a 10 million worker deficit.

That's why companies of all sizes are going to great lengths not only to recruit Millennial talent, but also to retain the next generation of employees. The bottom line? There just aren't enough skilled and educated workers to go around. Combine that with the fact that boomers are hitting retirement age and that Gen X is a small generation, and it's clear why Millennials have become a such a hot employee commodity.

So once you have hired Millennials to work for you, how do you keep them? Here are five effective tips that front-line boomer, Generation Jones and Gen X business owners need to be aware of to effectively retain their company's valuable Millennial talent:

1. Constant Contact: Robert Half International and Yahoo! HotJobs polled more than 1,000 Millennials about what they wanted from an employer, and more than 60 percent of them responded that they wanted to hear from their managers at least once a day. That message is pretty clear: They want to communicate with you often. So make it happen, or they will leave. Unfortunately, older generations tend to operate differently, with a hands-off approach to management. This style clearly does not work well with Millennials.
   
   
2. Praise Culture: We all need praise from our employers, but Millennials tend to need it more often than older generations. If they are not feeling "valued" on a regular basis, they will leave. Many well-known companies are shifting to a "praise culture" to retain them . . . and it improves retention of their older employees, too. Get creative and have fun with this. I know of one company that actually appointed a "celebrations assistant," and her job is to throw confetti on employees (in their cubes or offices) whenever a manager tells her that an employee has done something exceptional.
   
   
3. Rapid Advancement: Millennials feel that having to "pay their dues" is just occupying space for no good reason. So if a Millennial employee is truly qualified for a promotion, many companies now offer it to him or her vs. giving the position to someone who simply has been at the company longer.
   
   What if they're not qualified to move up the ladder yet but are getting antsy? Give them more responsibility through creative ideas: Have them start the company blog, set up a company page on Facebook, think of ideas about how the company can be on YouTube, write an ongoing column in the company e-newsletter; or research and set up a new software solution that improves productivity. You don't always have to give a raise or promotion to keep them happy; being creative with increased responsibility can work great. The bottom line: Millennials have fast minds and get bored quickly. And it's your job as their employer to come up with a way to avoid the boredom factor.
   
   
4. Cubicle Shackles: Millennials have a very hard time understanding why they need to be sitting in a cubicle eight to 10 hours a day to do their job. With modern technology, they want the flexibility to work anytime, from anywhere and not always have to sit at their desk to get work done. Many companies are revamping their policies to provide more flexibility, and they're also using that flexibility as a recruiting "perk" to attract Millennials to their work force. The upside? Employees of all generations respond favorably to this flexibility, and employers find that employees become more productive . . . and put in longer hours.
   
   
5. Mentor Programs: This is key! Millennials have grown up with a lot of guidance from their parents, society and teachers. They now expect this type of hand-holding at work. So, heed this advice. If your company, large or small, doesn't offer a formal (or informal) mentorship program, create one. I have spoken to many Millennials who have left a job because mentors aren't available. Think I'm kidding? I recently spoke to three Millennials who had been heavily recruited because of their grades and education, but who quit their jobs because they were promised mentorship and never received it . . . it truly means that much to them.

Millennials don't actually want anything that much different from older generations; they just have a lower tolerance threshold than generations before them. Plus they feel comfortable asking for what they want early on in their career--a Boomer may put up with a job for five years even if she is bored or doesn't feel valued, but a Millennial may only tolerate it for five months.

Lisa Orrell, The Generation Relations Expert, is a corporate speaker, consultant and professional leadership and career coach for Millennials. She is the author of "Millennials Incorporated" and "Millennials Into Leadership." Lisa has been interviewed for ABC, MSNBC, NPR, The New York Times, The Wall Street Journal, TIME, BNET.com and FoxBusiness.com. Follow her on Twitter @GenerationsGuru or follow her blog.