Unfortunately, moderate still feels extreme to me and constant means having to be singleminded if not obsessive. So, normal, as in occurring naturally, isn't a term that fits for me.

I agree that building muscle will help the metabolism. And, exercise, whether it is building muscle or doing cardio, is psychologically rewarding because it is active and can give you a dose of endorphins. Exercise and endorphins are linked to feelings of well being.

Better living through chemistry.