Keeping your workers engaged is essential to running a successful business, and every manager needs to stay focused on this goal.

Knowing what makes employees quit — and then heading off those problems — is the goal of every HR department. While you’ll never be able to avoid individual events that disrupt the lives of workers and their families, it’s helpful to have an overview of preventable causes for employee churn. People leave jobs for several classic reasons, according to Harvard Business Review, all of which are somewhat predictable. The key is to understand each reason well enough to defuse it with a proactive intervention. Here are the main reasons workers cite for leaving their positions, and how you can slow this expensive leakage and build your employee retention:

They Don’t Get Along with Their Boss

This reason is the elephant in the room, and we can’t discuss employee retention without starting here. Gallup CEO Jim Clifton points out the primacy of management know-how: “When you name the wrong person manager, nothing fixes that bad decision. Not compensation, not benefits — nothing.”

When an exit interview or other feedback shows that you have a problem manager, you need to rectify the situation as soon as possible. If the person seems open to developing new skills, it’s often worthwhile to provide them with intensive management training. However, if real change doesn’t seem possible, you’ll ultimately save money by replacing them with someone who simply has better management skills.

Their Lives Take a New Direction

This may be unexpected, but research cited in Harvard Business Review notes that job-hunting rates jump by 12 percent right before a worker’s birthday. Researchers speculate that a person is often stimulated by the arrival of their birthday or another milestone to take stock of their life and see if their career is going in the direction they want. While you have limited input into this private self-examination, it’s helpful to incorporate a personal check-in along with celebrating your employees’ birthdays. Are they happy with their job? What are their current thoughts and ambitions?

Their Careers Aren’t Moving Forward

In today’s networked marketplace, your most talented employees are going to keep an eye on opportunities in their field, and Gallup’s 2017 report on the State of the American Workforce  finds that 51 percent of them are ready to jump ship at any given moment by actively looking for a new job or watching for openings.  Harvard Business Review notes that Credit Suisse responded to this tendency by having their internal recruiters cold-call employees to let them know about new openings arising within the company that they might be qualified to fill. This program ended up moving 300 employees into more challenging positions and saved the company $75 to $100 million in employee turnover costs.

They Don’t Feel Challenged

Human resources expert Susan Heathfield warns employers that they have to make sure their workers are actually using their skills and abilities, and Gallup’s report found that 68 percent of today’s workers feel they’re over-educated for their current positions. While this is related to building a career path, it’s not the same. A position may have a title that looks great on a resume, but if the day-to-day operations don’t actually feel interesting and engaging, the worker is going to be looking for the exit door. Heathfield notes, “Work closely with employees who report to you to ensure that each employee is engaged, excited, and challenged to contribute, create, and perform. Otherwise, you will lose them to an employer who will.”

The Company Lacks Vision

To keep great workers, you have to make it possible for them to feel aligned with a company vision that’s both meaningful and tangible. Gallup CEO Jim Clifton, in his foreword to the 2017 report, puts it succinctly: “Change from a culture of “paycheck” to a culture of “purpose.” Your very best employees are the ones with a powerful sense of internal motivation, and you nurture that motivation by showing them how their efforts contribute to the overall goals of the company. CNBC notes, “Some of the most successful companies are able to attract and retain great employees because they are great at communicating their vision all the way from the top down to the front-line workers.”

Their Efforts Aren’t Recognized

While it’s essential to give your employees the sense of purpose mentioned above, that alone is not sufficient. Even your top workers, who care passionately about doing a good job, still have a psychological need to be recognized for the effort they expend. Emotional intelligence leader Travis Bradberry comments that a failure to recognize good work is one of the biggest mistakes a manager can make. He writes, “It’s easy to underestimate the power of a pat on the back, especially with top performers who are intrinsically motivated. Everyone likes kudos, none more so than those who work hard and give their all.” Establishing a system for employee rewards and recognition is fundamental to nurturing those human resources that your company is lucky enough to have.

In today’s tight labor market, it’s more expensive than ever to lose a good worker. Josh Bersin of Deloitte points out that employees are “appreciating assets,” while the cost of losing one is generally about 1.5 to 2 times the person’s annual salary. Furthermore, the increasing team emphasis of many workplaces makes it harder than ever to integrate a new hire. Keeping your workers engaged is essential to running a successful business, and every manager needs to stay focused on this goal.