The endocrine system is in charge or regulating hormones throughout the body. There are few organs that do this.
- pituitary gland
- adrenal glands
- pineal body
- reproductive glands
Hormones regulate mood, energy and even play a large part in cognition. Mental disorders such as depression and anxiety can all be summed up to one thing: hormonal imbalance.
Interestingly enough the nervous system and the endocrine system, even though they are entirely separate, often time work together. The nervous system is in charge of movement, mobility, and locomotion. Any sort of movement is going to stimulate hormone production. At the same time though hormones make you want to move. The body works well with itself.
Exercise and movement keeps the endocrine system healthy. That is reason enough to exercise there. Do it for the hormones.