Without exercise, the body just withers. It is built to move and the more movement it gets, the healthier (and happier) it is.
The good thing is that it is never too late to start. Even an unused body will quickly adapt to exercise.
It is even a great antidote to depression.
I agree with you about exercise lightening one’s mood. It is hard for me to get out the door for a run, but I am always glad it did it!!