It doesn’t take a string-theory physicist to understand a basic management truth: Employees who feel they’re recognized and rewarded for their work perform better and are more likely to become something that’s less and less common these days — loyal, long-term employees.

But if this is such an obvious concept, then a lot of organizations still are missing the proverbial boat. According to the latest Globoforce Workforce Mood Tracker report, 42 percent of survey respondents said they’re looking for new positions, despite the poor job market. The second most popular reason for leaving — cited by almost half of the respondents — was lack of recognition at work. And a whopping 82 percent agreed that getting recognition makes them feel more satisfied about their jobs.

“Rewards and recognition are valuable tools for managers, but they often overlook them or don’t recognize their value,” says Carol Hacker (www.carolahacker.com), a nationally known business consultant, speaker, seminar leader and author of 14 books, including 450 Low-Cost, No-Cost Strategies for Recognizing, Rewarding & Retaining Good People. “To employees, rewards and recognition are comparable to oxygen — everybody needs it to survive.

“If you’re not willing to reward and recognize people, you’d better look around because a lot of other companies already are … and your employees are going to jump ship and go to where they can find those things,” she adds.

OK, so far, so good. But what about budget-strapped organizations, where cash bonuses are about as likely as self-cleaning, no-clog sewer mainlines? Well, it turns out that rewarding employees is similar to giving gifts: More often than not, it’s the thought that counts, not the size or value of the gift, Hacker notes.

That’s not to say that giving an employee a 10 percent cash bonus will make them unhappy. But most employees understand that because of budgetary constraints, that’s not realistic. And cash bonuses don’t have what Hacker calls “trophy value” — something tangible they’ll always remember. (Free tip: Don’t even think about handing out company-branded merchandise like T-shirts and coffee mugs.)

In fact, some studies show that employees would gladly forego monetary bonuses for more freedom and decision-making power. As such, delegating more responsibility to employees who want it, or giving them the power to make decisions about things that impact them directly, are both powerful motivators, Hacker says.

When considering rewards and recognition, managers also must consider the individuals involved. Older Baby Boomers, for instance, would appreciate certain rewards that Gen Xers or Yers would disdain, and vice-versa. The bottom line: To make sure you’re hitting the right reward-and-recognition buttons, there’s nothing wrong with asking employees what rewards they find meaningful, she points out.

Another thing to consider, Hacker suggests: Like the old adage says, there’s no “I” in team. As such, rewards for team accomplishments should recognize the entire team — take the whole group out for dinner or have a free lunch brought into the office, for instance — lest an individual reward provoke claims of favoritism from resentful colleagues. Afterward, managers can informally poll team members to see if there’s prevailing sentiment that an individual deserves some sort of additional recognition.

During Hacker’s more than 20 years of consulting, she has observed hundreds of clever and inexpensive ways that organizations use to reward employees. Here are some of her favorites:

Hold an employee recognition day (or week). This could include a small surprise each day for each employee in your department. For example, Hacker says she used to put department vending machines in a break room on free vend for 24 hours for coffee and soda. “The employees loved it,” she recalls. “You would’ve thought they’d each received $100. And it only cost me about $200.”

Weekly or monthly privilege grab bags. Write down desirable privileges/rewards on pieces of paper and have employees blindly draw them from a paper bag. Options could include leave work a half hour early on a Friday. Take 15 minutes extra for lunch. Come in 15 minutes after start time on a certain day. Get a free lunch with the boss. “As simple as it was, it was such an energizing thing,” Hacker says.

Public displays of achievement. Hacker says that while visiting a Fortune 100 client years ago, she came across a huge tech center, filled with a sea of gray cubicles — and a ceiling covered with streamers. Turns out that every time a team hit a production goal — say, cleaned x amount of sewer lines in a week ­­— they got to tack up streamers to the ceiling and have a brief but boisterous celebration. “As crazy as it sounds … production skyrocketed,” she says.

Build-your-own sub sandwiches or ice cream sundaes. To celebrate an achievement or the end of a business quarter, bring in ice cream and toppings or buy sub-sandwich rolls and fixings, and have managers man the tables and hand out bowls, spoons, etc.

Create an Employee Wall of Fame. When customers — or colleagues and supervisors, for that matter — submit compliments about employees, display them prominently on a bulletin board in a high-traffic area.

Small job-well-done treats. If someone does a great job on a project or goes above and beyond the routine to help out a customer, pass out Kudos candy bars. If an employee comes up with a “lifesaving” idea, give them a necklace made out of Lifesavers.

Head-honcho note. At the end of a new employee’s first week on the job — or if someone does something noteworthy — have the head of your organization send them a personal, hand-written thank you note. “I have a client where the president of the company has sent personally written notes to hundreds of employees, thanking them for their accomplishments,” Hacker says. “But the note should specify exactly what the thank-you is for … that gives it a lot more power. And it doesn’t cost a cent.”

Of course, creative managers and organizations can think of hundreds of other ways to recognize employees with rewards tailored to specific occasions, achievements and people. Sometimes something as simple as compensatory time off for employees who’ve put in long hours on a grueling project will do the trick.

But in lieu of nothing else, there’s always this old tried-and-true concept: Personally thank employees for what they’ve done. In the end, employees simply want to be treated with dignity and respect, and few things resonate more with employees than a manager or supervisor who takes them aside and personally expresses appreciation for a job well done.

“There’s no substitute for the words, ‘Thank you,’” Hacker notes. “And most employees don’t hear it often enough. And what does that take to do that? Not a whole lot.”