Now's not the time to let employees jump ship. Not only is the unemployment rate hovering in the record lows, but it's also getting even more expensive to replace employees. 

Replacing workers cost employers $617 billion in 2018, compared with $331 billion in 2010, according to The Wall Street Journal, citing a report by Work Institute, a consulting company.

What this means is that even if the economy slows this year, it's becoming all the more vital to retain key employees--that is, of course, if you want to keep additional costs to a minimum. And what business owner doesn't want that?

Here are four budget-friendly ways to keep employees happy and engaged.

1. Provide flexibility.

If you don't already offer flexibility to your employees--and if it's at all possible--it's time to start now. People want to work from home, come in, and leave at different times, and not get yelled at for taking a two-hour lunch from time to time. Yes, reliability is important. Yes, getting the work done is important. But make sure you're looking at results and not at time-in-seat. 

2. Offer stability.

This may seem the opposite of the first suggestion, but depending on your industry, it might be critical. If your business needs different staffing levels at different times, the varying schedules can drive your staff crazy. It's difficult to arrange child care if you work a Tuesday morning, a Wednesday afternoon, and a Thursday evening. Try your best to give stable schedules so your employees can plan their lives.

3. Train your managers.

Regardless of how high the paycheck is or how exciting the work is, a bad manager can turn a good job into hell. Make sure your managers know how to manage. Train them on feedback. Stop any bullying immediately. Fire bad managers. Yes, it's expensive to replace them, but if one lousy manager drives out five employees, it's far cheaper to replace the bad manager than all the staff.

4. Manage workloads.

Yes, this can run into expensive solutions, but again, how many people will you lose if you are working them to death? Some industries have busy seasons when 80-hour workweeks are standard. Fine. But if they're working 80 hours the entire year, your workloads are out of control. If they are working 60 hours a week all the time, you need more employees. People with manageable hours will do better work. You can't be as productive when you're exhausted.

Make sure you look to find ways to make your employees' lives better, and they'll be happier to stick around. And please stop with the mystery meetings. It just causes everyone stress.