You may not ever face your evil twin in an actual physical battle, as in the TV show. However, the reality is that you possess, in your mind, an entire gamut of potential behaviors ranging from good to evil, and all variations along the continuum. You endure a constant struggle to prevail against your “evil” within - meaning, the eternal antagonists of inattention, laziness, hubris, cowardice, apathy and so on. Your “good” virtues of courage, industry, attention, strength, etc. wage a never-ending battle against their polar opposite.
When you recognize and acknowledge this struggle within, your first step toward triumph is taken. The key is to defeat your “evil” side with displays of the “good” attributes. Each time you act on behalf of the good, you are made stronger. This strength expands and builds upon itself in an exponential manner, to the extent that the “good you” can make the “evil you” its friend, ally, and even slave. Together, you are unstoppable. Use everything within, and become great.
From September 2010, http://raising-a-man.tumblr.com