Achievements are simply examples of what God can do through someone's life. The most effective leaders spoken of in the Bible had little awareness of the impact of their lives on others. They were too busy obeying God to keep track of their own successes.
Great leaders, through whom God does great things, put themselves in positions to be used by God like that because they dedicate themselves to studying God's Word, they lead with the intent to make practical application of God's Word, they are purposefully obedient to God's Word and finally, they teach God's Word to others. It is through this "to do" list that they become most useful to God.