“For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand so that we would walk in them.” Ephesians 2:10 (NASB)
While we read and think on this verse let’s be sure to notice that the emphasis is on God and His plans for us. It’s not on what we do for God but on what He does for us. ‘Good works cannot produce salvation but are subsequent and resultant God-empowered fruits and evidences of it.’1 When the verse speaks of our being created by God it really means our being born again – our re-creation because of what Jesus did for us. It is God who makes that happen and makes us His child and give to us eternal life. That makes us the work of God – we are His workmanship. ‘Like his salvation, a believer’s sanctification and good works were ordained before time began.’2 God has a purpose in this and it is that we will do what He gives us to do. We will tend to the work He gives us. Good works in our lives comes after His work in our lives. And all this was prepared and planned in advance. It is God’s plan that comes together for our benefit.
  John F. MacArthur Jr., The MacArthur Study Bible: New American Standard Bible., (Nashville, TN: Thomas Nelson Publishers, 2006), Eph 2:10.