I've always loved this verse. I believe that I alone cannot be strong and courageous without the Holy Spirit who empowers me. So whenever I read this, I am reminded that BECAUSE I have the spirit, I am capable of being strong and courageous.
Colossians You must depend on Christ only, drawing life and strength from him. Just as you were taught the truth, continue to grow stronger in your understanding of it. And never stop giving thanks to God.