From Fitbits and other wearable fitness trackers bursting onto the scene five years ago, to mindfulness apps that lead users through meditation practices, to the emergence and proliferation of the modern-day yogi, we've all been riding the wellness wave in some way or another.

Employers' role in wellness has evolved during this time, too. Many companies started offering wellness programs to improve employee satisfaction and engagement – and were often as simple as establishing walking groups. However, more businesses began to recognize the value that such programs can bring when taken seriously.

As a result, employee wellness is now an $8 billion industry in the United States, promising companies to improve the health of their workforces and, in the process, secure a good ROI by reducing overall health-care costs. These programs range from nutrition and exercise advice, to smoking cessation and weight management.