Ambiguous

At what point do we transcend the grey area between selfishness, and selflessness? Is it not righteously essential to success to do so? Is it possible, for both you and your peers to rest assured your best interests are served?
In separate stages of my life I have found it necessary to be either or; selfish or selfless. At either end of the playing field you'll find yourself on the offense, struggling for confidence in your defense, often times praying for the sack from a higher power in the form of answers.
Is there success in the ambiguity of this purgatory?