It's impossible to overvalue fantastic employees. These team members are always on time. They hand in impeccable work. Their attitudes are always positive and uplifting. And research shows that they also experience less stress.

An August VitalSmarts survey of more than 2,000 managers and employees asked them about co-workers they would rate a 10 out of 10. About half of both managers and peers said these '10' employees worked both harder and smarter. On top of that, 75 percent of leaders and 63 percent of peers said that the best employees have the same or lower stress levels than average employees.

I repeat: the best employees are more productive and happier.

That's a powerful statement. In other words, create a work environment that supports not only the top employees but everyone.

As you're looking ahead to 2018, here are four ways to keep all employees at their best:

1. Do as you say.

You can't expect employees to be at their best if you are not. As Kerry Alison Wekelo, the managing director of human resources and operations at Reston, Virginia-based financial consulting firm Actualize Consulting, pointed out that a productive culture starts at the individual level.

"You must thrive personally in order to lead others effectively," she said, "whether you're a top-level executive or lead a team."

This starts with prioritizing your own personal wellness. If your company has a wellness program -- and it should -- participate. Make sure that employees see you taking the time to stay healthy and happy.

If you have a wearable fitness device, post your daily step count somewhere in the office. This will inspire all employees to exercise. After all, if a busy leader can make time for their health, so can they.

Also, acknowledge your own daily accomplishments. Be a motivational example for your employees. When they see you celebrating because you've hit goals, they'll understand that it's acceptable to toot their own horn. This will keep their motivation high and allow them to maintain a high level of productivity.

2. Trust the system.

Just as every team has its own culture, it also develops its own processes for how work is done. Finding the right one will set everyone up for success.

For example, Menlo is an Ann Arbor, Michigan-based technology industry consultancy firm. The team has managed to erase bureaucracy with a system of colored stickers.

Each week, team members are paired together on a single project. Then each pair plans out their work on index cards that they display in the office. As they work through the week, they use colored stickers to show themselves and each other how they are progressing.

Rich Sheridan, the CEO and chief storyteller of Menlo, says the best way to increase productivity is to develop systems that work for employees. This allows employees to focus on what they're achieving every day.

"Spend less time discussing new ideas and more time actually trying them to see what works and what doesn't," he said. "When you find things that work, do more of it."

3. Foster peer praise.

Co-workers matter. These are the people your employees spend the most time with, so their approval can mean the world. If you're not using some form of peer recognition program, you're ignoring a powerful motivational force.

LiveStories is a civic data company based in Seattle. More than a year ago, they implemented their clutch award program. As part of this initiative, each employee gets $50 every month. Then they give it to a co-worker they feel has gone above and beyond. The recipients are also told what they did to deserve the acknowledgment.

"Recognition is paramount," said CEO Adnan Mahmud. "People want to know that their hard work matters. Recognition also encourages other employees to step up and take on more."

4. Water the seeds of growth.

Top performing employees want a challenge. They need to grow and try new things. This means having training programs in place so they can learn and push themselves to do more.

At the San Francisco-based online retail sales platform Narvar, senior leaders receive training to spot and develop employees' strengths. This allows individuals to stay engaged and productive, no matter their role.

"One of our customer success managers wanted to transition to business strategy," CEO Amit Sharma said. "We'd worked closely together, so I recognized she was doing well in her current position and she had the potential to do well in strategy."

After some training, the woman transitioned into the new role and continued to be a productive team member.

"When we find a talented employee, we want him or her to thrive at Narvar and stay here for the long haul," he went on to say. "If employees are performing well and will do well in another role, we'll support them."