Here is my point of view.
This wellness program at big corps is a strategy for better productivity. This program is more considered where a big company's employee's health cost is soaring (due to higher employee-insurance claims, off-work, more sick leaves, lower productivity, etc). Meaning, the attempt is to, increase productivity while decreasing the employees' healthcare cost. Nothing comes free in the corporate world (same applies to employees as well, as the cost is is included in their pay one or other way).
Some companies choose one or more of, nap rooms at work place, monthly team building trips, 1000-2000 cash bonus if employee had an annual health-check and turned out be healthy, cash payments towards a membership purchase for a wellness program (like gym membership, gym equi. purchase, etc) , flexible hours, team building holiday trips/vacations, etc.
There are several to choose from, but the bottom line is to increase productivity at work. Nobody gives a damn about employee's wellness, as it is totally personal choice to be active and healthy. No hard feelings, but it is true. Otherwise we would not have seen America in the list of countries with high rated obese population.
Be clear with your employees and take a feedback from them how many would be interested. If you go ahead with investing a heavy amount in it and nobody wants to do it, then it would turn out to be an expensive thumb-down.