If you see a "therefore," ask why its' "there for." What Paul is saying in a kind of conclusion to what he has been writing about, is that if we are to live lives that are "worthy of our calling" then imitate your Heavenly Father. Live as you believe He would live on this earth. And since we represent the Lord, (see 2 Corinthians 5:20), we should allow the world to see God through us.
How do you "imitate" God? First, you need to really enjoy a personal walk with the Lord. You need to know Him as a God who is close to you. You need to spend time learning from Him about Him! Get to know not only Who God is, but also what He is like. Second, make it your purpose to face life and handle each situation as God would. But remember, Jesus said, "...without Me, you can do nothing." (John 15:5) and Paul said, "I can do all things through Christ who strengthens me." Expect God to help you live out this verse. He wouldn't say for you to imitate Him if He didn't mean it could happen!