Only second next to Brian Tracy in number of books written on life effectiveness, John Maxwell is a major compiler, explainer, and determiner of what it takes to be effective.

Before I further fill this page (which I will do later as it fits into programs I create), I would urge you to review a list of all the books that he has written and select those of interest to you (in priority order) and then read away!  You'll become wiser much, much faster.  Start with this list on Amazon:   John Maxwell books.  

Interestingly enough, like many of the progressive minds in this world, he started off in a "cause".   He originally followed his father into the ministry.  He wrote a few religion oriented books, and then he started writing secular, practical books that are not religious themed.