Losing a great employee is a major blow to your organization. Replacing employees is expensive, thanks to onboarding and training. There's also the possibility that the new hire won't pan out. And, you're asking your existing employees to handle additional work until a replacement has been found.

You can, however, avoid this problem if you're aware of the main reasons why your top-performing employees quit. Armed with this knowledge, you can develop a workplace that encourages them to stay for the long haul.

1. Relationship with the boss.

It's not expected to be BFF's with the boss. However, there does have to be a healthy and positive relationship where leaders provide feedback and direction, recognition of hard work, and encourage employees to enhance their skills.

Even if the boss is a great person, they may lack the leadership skills to keep employees happy and engaged.

2. Imbalance of work/life.

A healthy work-life balance is one of the most effective ways in retaining employees since it prevents burnout, reduces stress, and allows them to recharge their batteries. After all, why would an employee want to stay with an organization where they're penalized if they have a doctor's appointment, have to take care of their sick child, or have no time to themselves.

Even if they love the job, employees demand an organization that's flexible enough to meet their personal obligations.

3. Inequality.

Even though we've made progress over the last couple of decades when it comes to discriminatory problems, there are still instances of inequality, such as the sexual harassment claims.

Employees demand a workplace that is tolerant and progressive and one that addresses inequality head on.

4. Overworked or under worked.

It's not uncommon for outstanding employees to go above and behind. They'll do more than what was initially asked of them without complaining. The problem is that eventually, the overwork becomes too much for them to handle -- which is a surefire way for them to punch a one-way ticket to Burnoutville. Employees should be encouraged to hit the brakes from time-to-time so that they don't overextend themselves.

On the other hand, there are some employees who are able to complete tasks so quickly that they have nothing else to do, which can lead to boredom. While employees deserve a breather, they should never feel bored. If they have nothing to do, then foster an environment where they always doing something productive, like attending a webinar or workshop that can help them develop new skills.

Always have training videos available so that any employee can access these and up their skills in those extra few moments of freedom. Perhaps they will choose the video for ten minutes of their lunch breaks.

5. Treated like a cog in the wheel.

While factors like profits, output, pleasing stakeholders and productivity are all vital to the success of a business, they shouldn't be the only priority of the organization.

Employees don't want to be treated like a cog in the wheel. They want to be respected, motivated, paid a fair wage, feel like they are providing a real contribution to something bigger than themselves, have a life outside of work, and be treated like a human being.

6. Bored and unchallenged.

Leaders should always ensure that their team isn't bored or feel unchallenged. This doesn't mean that you assign more work. It means that you should find out how to keep them engaged, excited, and challenged.

That's why you see companies like Verizon, Ford, Qualcomm, and Hasbro using hackathons to increase collaboration, as well as give employees the chance to pitch ideas and think outside of the box.

7. Promotion issues.

Don't be surprised when an employee hands in their resignation letter because they were overlooked for a promotion. This is especially true when this employee was a high-performer and the promotion went a colleague who isn't as talented, motivated, or experienced.

"If you choose to have an organization with fancy titles and a hierarchical system, then you are going to run into these problems, says Matt Wilson, Co-Founder of Under30CEO. "There is no good solution to sugarcoating the news to someone that their former colleague is now their boss. In this day and age, there is no reason why we have to have a corporate-looking system of promotions, instead of everyone just accepting more responsibility."

8. Feeling trapped.

Even if the employee is happy with the workload, type of work, and organization, they may eventually feel trapped by being stuck in the same daily routine. To prevent this from happening, shake things up.

Assign new responsibilities, have employees switch roles occasionally, and implement a more flexible schedule where they can set their own hours or work from home a couple of days a week.

9. Aren't recognized.

We all want a pat on the back every now and then - even those who are intrinsically motivated. It could be as simple as a "thank you" to something more elaborate like an award. The best leaders take the time to know their employees so that they know what type of gratitude works best for them.

10. No career progression.

As already mentioned, people don't want to feel trapped in their jobs. They want variety. They also want to know that they're not going to be stuck at the same position for the rest of their careers.

Promotions have been used in the past, but if you really want to retain top performers, offer training and educational opportunities so that they can strengthen their existing skills or develop new skills that will make them more valuable to your company.

11. No empathy.

When employees have a question regarding a task, a personal problem, or an issue with a coworker, leaders need to show them empathy by listening to them and coming up with a logical solution.

12. Toxic work environment.

A toxic work environment includes interpersonal conflicts, gossip, interoffice competition, or an unsafe workplace.

Again, leaders need to be cognizant of these problems. Pay attention to any conflicts, listen to your employees, and discourage competition.

After listening to these problems, come up with solutions like letting go of toxic employees or moving the employee to a different part of the office.

13. Stingy benefits.

Generous benefit packages, like health insurance, sick days, vacation time, flexible schedules, paid maternity and paternity leave, and funding for professional development, are just as important to employees as a good salary.

However, benefits can also be as simple as offering employees free snacks, a gym membership, and allowing them to bring their dogs to work.

14. Forgotten commitments.

When leaders uphold their commitments, they prove to their employees that they're trustworthy and honorable. When they don't, they come across as disrespectful and uncaring.

15. Aren't encouraged to pursue passions.

Passion projects are an effective way to keep employees engaged and motivated. That's why Google, Apple, Microsoft, and LinkedIn have all at one point launched programs where employees could spend a portion of their workday on a side project. As an added perk, companies may implement these creative ideas into their organization - just like Google did with Gmail.

Another way to encourage passion is by offering volunteer opportunities for employees. Instead of going to the office for the day, employees would volunteer at a nonprofit that they care about.

16. No effective motivation.

Employees aren't just motivated by a salary. They may be motivated by recognition, benefits, or working on a passion project.

Effective leaders know what motivates each specific employee and will develop motivation techniques for that individual.

17. Lack of opportunities to use skills and abilities.

Employees have a sense of pride, accomplishment, and self-confidence when they're able to use their skills and abilities - even if it's not their job description.

For instance, do you have someone in bookkeeping who has a knack for creating YouTube videos? Then give them the chance to film a series of YouTube videos as a part of your content marketing strategy.

18. No training.

Even though you hire a talented coder, that doesn't mean that they still don't need some type of training. They may not currently need more coding skills, but they need to know how to operate within your specific organization, like who they report to, how payroll is handled, etc.

19. Aren't contributing towards the organization's goals.

Employees want to be assured that they're an important part of the organization's bigger picture. It gives them a purpose and builds a connection to the overall organization. Effective leaders clearly communicate to their employees how they played a role in achieving milestones that connect to the big picture.

20. Not challenged intellectually.

Instead of setting mundane and incremental goals, great leaders set goals that push employees outside of their comfort zones so that they won't get bored. In fact, according to one study, not being challenged is the number one reason why employees jump ship.

Additionally, great leaders provide the resources needed to help their team achieve these goals. Again, that's why hackathons have become so popular.

21. Lack of independence.

While effective leaders are there to provide support and guidance, they also give their employees the opportunity to take the ball and run with it. It's a simple and powerful way to demonstrate that you trust them enough to work on projects on their own because they have the talent, skills, and expertise to handle the task without holding their hand.

22. Meaningless work.

This isn't always a challenge when working with organizations that are making a difference in the world, such as cancer research, producing renewable energy, or providing low-cost technology to developing countries. But, how can you demonstrate that your company is asking your employees to do more than just busy work?

Explaining how their work is assisting the bigger picture is a start, along with developing a culture that reflects the company's value. Take Zappos, for example. Their mission is to do whatever it takes to make the customer happy by allowing customer service reps the freedom to make their own decisions.

As a result, the reps have more meaning to their work than just handling refunds or answering questions. They're part of a culture of happiness.

23. Excessive hierarchy.

While every workplace requires some structure and leadership, a rigidly top-down organization will only make employees unhappy. Employees are seeking to work for companies where the reins are loosened so that they feel more empowered.

24. Financial instability.

How can employees trust your company, and be willing to stay, when sales are low, there are numerous layoffs or reduced work hours, salary or hiring freezes, bad PR, employee turnover, and rumors of the company merging or being acquired?

Always be transparent with employees. Don't sugarcoat the fact that times are tough. If it's temporary, then lay out your plan on how you're going to recover.

Remember, they have their futures to worry about and want to be assured that they're not onboard a sinking ship.

25. Changing career goals.

It's normal for people to switch careers. In fact, a majority people born between 1957-1964 have had 11.7 different jobs between the ages of 18 and 48.

Offering employees that chance to learn and develop new skills is one way where you could convince them to hang around since it allows them to switch careers within your organization when they have the itch to move on.