I would have to say that one of my favorite verses--one that has had tremendous impact on my walk with God is Romans 12:1-2:
Transformation doesn't happen overnight. It takes time, and for me it has at times seemed agonizing, and at other times seems uneventful. However it is beginning to become apparent to me that God is and has been at work within me. That if I let Him, He will transform me. My thought life, though not perfect, is noticeably different.
I am so grateful that God is at work within my life, and has sustained me through so much. I pray that next time I doubt God's work in my life that I would be able to reflect back on all that He has done for me--and how I did not deserve any of it.
Below is an interesting excerpt from a website I came across:
Do you believe that sharing the Gospel is urgent? If you don’t, then your mind needs to be renewed. When you look at the people in your daily life who are unbelievers – your co-workers - your relatives – how do you see them? They may be nice people, and you may even think of them as successful - yet are you able to see them in their true condition - held captive to the Devil, under the wrath of God, and headed to an eternity of unspeakable torment from which there will be no escape? Do you really believe that you have eternal life? Are you persuaded that you will never die, that you will live eternally in the presence of God? Only then will you live fearlessly for God. Or as the Proverbs say, “You will be as bold as a lion!” But if you think that this life is all there is then you will love this world and you will live to gratify your own desires. Are you a believer? And yet are you easily offended? Do you fear the rejection of others? Are you in bondage to what others think about you? Renew the mind! Think about yourself the way God thinks about you. Realize that you have the unchangeable favor and acceptance of Almighty God. This is the only true security. It does not matter what mere people say. It does not matter what they do! Nothing can harm you, because “if God is for us, who can be against us.”