Is weight control the primary benefit of exercising

Heck no!  Your heart gets a work out and exercise helps with diminishing depression.  There are more benefits too.  It is not just for weight control.

1.)dr. natterson- horowitz came to realize that their isn't much of a difference between animals and humans. just like humans, animals can suffer from illnesses and diseases like breast cancer, self injury, anxiety, and many more. she also discovered how they even treated and performed surgical procedures on animals just as if the animal it self were human. the los angeles zoo called dr. natterson- horowitz because they knew that she was a doctor and that  she would be able to recognize what was wrong with the gorilla. they knew that humans and gorillas were similar, so instead of calling another veterinarian, they called a doctor.