Think about God's love for you! Jesus did not extend to you the gift of salvation because of your skills, talents, accomplishments, or any other feat or attribute. The truth is that our sins make us wholly undesirable and completely deserving of abandonment. And yet He looks upon us and chooses to love us; not for what we've done, and not for what we might one day accomplish, but merely because He is great and glorious, and by extending His love towards us worthless wretches it demonstrates His glory to all of creation.
Do you have the humility in your heart to recognize your filth, and the greatness of the completely undeserved mercy He has poured out upon you? And as you ponder this, does it not begin to transform your heart towards Him and others? How can you go on looking at the other "sinners" in your life and still think of yourself as somehow better than them, or more deserving of His grace? We are all equally worthless, and yet have been ascribed the utmost value, having been purchased by His blood. We are like filthy rags being sold at an auction for millions of dollars; how can one filthy rag look down upon another?
We will one day stand before our Lord, and when that happens the last remnants of our old sinful selves will be destroyed, and we will fall to our knees crying tears of joy which our Lord will lovingly wipe away. But until that day, fix the eyes of your heart on Him, remembering the depths from which you were bought, and allow humility to reign in your heart so that you can extend to others the same mercy that you've found.