Another reason what we do is important is because God has entered our heart and changed our spiritual DNA. If God is in our DNA, then there should be a ripple effect through out our lives.
A change in DNA means a change in how the process of the body functions, a change in the body's programs, if you will. This change demonstrates the reality of our choice to follow God.
One of the main areas of change is in our "want-to." Our motivations change. The things we want to be involved in change.So, if we do not care about our lifestyle (how it agrees with Jesus' teaching and example) then there is reason to consider that we have never chosen to follow Jesus.
There are people, who in the midst of emotional excitement or trauma, say they follow Jesus. Sometimes it is genuine. Sometimes, this is an attempt to bargain with God. "I'll do what you want, God, if you do what I want." A change of allegiance must recognize God's role and nature in the universe. That is, he is King and Ruler. We are choosing to submit to him.
We will never live this life we have chosen fully or completely. There will be slips, stumbles and falls. And, although no one else can see my motivations, it encourages me to realize that even my frustration with my failures indicates I am still motivated to seek, strive and follow Jesus as best I can. Which means he is still working in my heart. The steady process of re-creating my spiritual DNA still continues. If he still works, I am not rejected, I am accepted by him.