People quit their jobs for a wide variety of reasons. While every situation is unique, most of the reasons people quit their job are something the company should have controlled. When a good employee chooses to quit, it’s often preventable.

Employee retention is an important factor in any company’s success. The Harvard Business Review conducted survey data to predict the reasons employees stay or leave their companies. These insights might be useful for HR's fields. No employer wants to lose an employee. It’s disruptive, costly, and frustrating when they do. So based on the survey, here are 3 big reasons the best employees leave their companies.

They are looking for ways to bring passions into their jobs

Managers can play a major role in designing motivating, meaningful jobs. The best go out of their way to help people do work they enjoy — even if it means rotating them out of roles where they’re excelling.

A few years ago, one of Facebook’s directors, Cynthia, was leading a large team of HR business partners. She realized that she wasn’t spending her time doing what she enjoyed most: solving problems with her clients. She had taken on more responsibilities managing a large team because of her strength as a trusted adviser to some of Facebook’s key leaders. But once she was in the job, she realized it meant doing less of the work that energized her.

With her manager’s support, Cynthia hired someone new onto the team, with the long-term vision of asking her to run the team and then moving back to an individual contributor role. She wasn’t just hiring a direct report; she was hiring her future boss.

Once the new hire was ramped up and it was clear that she enjoyed her job's organizational and people management elements, she and Cynthia made the switch. Cynthia is now thriving, solving problems with the clients she loves so much, and her new hire is leading the team. Keeping Cynthia at Facebook was much more important to her manager than keeping her in a particular role.

Creating new roles isn’t the only way to let people play to their strengths

Smart managers create opportunities for people to use their strengths. Let’s consider Chase — who was recently working as a software engineer at Instagram — to see how that can play out.

About six months ago, when his team went through rapid product iteration to introduce new tools and formats, Chase helped lead the team to exceptional results. But he finished the project drained from the extensive coding and cross-functional work — and started wondering whether there were other ways to contribute.

Talking with his manager, Lu, he realized that while he had a strong technical background, he excelled in building prototypes to help prove concepts quickly and then iterating. But Instagram didn’t have any roles that blended this skill set, and Chase didn’t have a track record in traditional design work.

Lu convinced the design team to take a risk and allow Chase to try a new role for a “hackamonth”. During that time, Chase partnered with Ryan, a product design lead, to quickly build several prototypes that tested novel ways of capturing and sharing.

His success not only landed him in a brand-new role that leveraged his strengths but also created the conditions to build a broader team of collaborators with similar skills and interests. According to Lu, “A shift to this role was a no-brainer for Chase and a win for Instagram. All that was missing was the push to make this happen.”

Creating a positive work environment for the employees

In many situations, opening a door in our careers means closing one in our personal lives. The special project that takes date nights away from our partners. The big promotion that takes weekends away from our kids. The new role across the country takes us away from our families.

Shona, an agency lead, was returning from maternity leave to a global role where time zones directly conflicted with her parenting. With her manager, Shona developed a prioritization plan for travel. She worked with regional colleagues to set up meeting coverage for anything important but not essential.

Shona’s manager also connected her with a mentor in a global role who guided her through her transition. In Shona’s words, “This deep level of support gave me the confidence to return to work fully present and also be there for my daughter.”

Managers who give this kind of support find that their people not only deliver but also stay longer — they’re proud of where they work.