I would highly recommend the Art of War by Sun Tzu to anyone as a self improvement piece. There is no doubt as to why this is highly regarded by many sales and business people wanting to gain the edge.
Although, the text was produced with the battle in mind, a lot of similarities can be drawn to everyday life. We battle and struggle with ourselves everyday, as we do with others. Its not about life and death and is generally used in context with the selling your product, or how to present yourself to someone to get what you want (oversimplified summary I know).
There is a consistent theme throughout the book which I think is important to everyone and that is to know oneself and until we know ourself we can be our own enemy.
So if you are hitting a brick wall in your life (maybe trying to make or break a habit) why not try a different approach? Maybe looking at yourself and the problem from a different standpoint may reveal the path with the least internal resistance. Isn’t it always better than working with yourself to reach a goal than to work against yourself to do so?