The new generation of multi-family fitness centers in our quick-moving modern world becoming more sophisticated every year. Fitness centers are a must-have in any residential or active community, according to the National Apartment Association.    Residential gyms are the most upgraded community amenity since 2014, and research shows that half of all tenants would be willing to pay a higher premium for multi-family fitness centers that offer weekly exercise classes. 1. Treadmills Every multifamily property and business situation is unique but the n...