What can employers do to create a workplace that enhances the physical and mental well-being of employees?
Books have been written on this. It is not condusive to a paragraph answer. Additionaly, employers must enhance job performance first, thence other considerations such as these can be addressed.
Often, stress reduction at the work site can be reduced...that does not mean elimination of deadlines, but it does allow for flex hours, and team formation. It does allow for access to recreation facilities, and family events. It does allow for individualization of the workspace.
Good health plans go a long way towards the physical and mental well-being of workers.
Family consideration (special needs, etc) goes a long way to helping also.