Exercising too frequently can alter your recovery time and therefore hinder growth and performance. Rest is a must and without it, progress will come to a halt or worse yet, there is the strong possibility of injury or illness. In reading coach Phil Jackson's book, Sacred Hoops, there is an excerpt that is applicable to what I'm suggesting:
"The farmer who's so eager to help his crops grow that he slips out at night and tugs on the shoots inveitably ends up going hungry."
Think about how that can apply to your exercise program. - Fred Fornicola