A lot of people are only socially motivated to fitness: 1) With less socialization in general, less motivation towards fitness. (The "who cares if I am a fat slob if no one sees me outside of the house?" problem.) 2) Gym tools like personal trainers are an "accountability-buddy", a big reason why they are such a common gym amenity is that some people need that "mentor that keeps me accountable" or other peer pressures of a gym environment.

You can only do so much social motivation over Zoom.