I have found that a most affective way to live a successful life is to be in the right (or best) mindset at a given moment in time. If you are anything like me- you have read and studies many disciplines during your journey called life. Mine spans the spiritual to the material to the philosophical.
Suppose you are feeling a little down. You may feel like you studied enough spirituality that you should not feel down. And yet you do. The mistake you are making is not being in the moment. The best mindset for the situation. That may mean pulling out Don't sweat the Small Stuff and meditating on a chapter.
Suppose you are trying to get a new contract for your business. You don't need 'Sweat the Small Stuff' now. You should pull a good marketing book or visit one of the masters like Seth Godin. That is putting you in the best mindset at the present time. That leads to a more successful life.