Acts 8 (Click on reference to read text - I know it is a long one today, but it was important to have proper context!)
Philip obeyed the Lord. He faithfully fed the widows and served in a seemingly menial task (Acts 6:1-6). When persecution in Jerusalem came, he went to Samaria to preach the good news. He saw great revival spring up and even the town's "sorcerer" believed and was baptized. Then Peter and John came down from Jerusalem. Although they confirmed his ministry and witnessed the many added to the church, they also discovered that "Simon the sorcerer" probably wasn't a believer after all. Philip could have become embarrassed, he could have felt like a failure and ceased spreading the good news, he could have given up, but he didn't. He was not concerned about the applause of men. He was only living for the applause of God.
There are times, at least in my own life, that when disappointments happen, we take it personally. We become embarrassed by the behavior of others under our leadership and view it as a reflection upon us and our leadership abilities. We begin to believe that there must be something inherently wrong with us. However, even Jesus, the greatest leader of all time, watched someone close to him (Judas) choose sin instead of eternal life.
Philip realized an important truth: we are responsible to be obedient to what God has called us to do, and then we must leave the rest up to God. We are not responsible for the actions or disbelief of others under our lead (although we do have a responsibility before God to point it out and give them a choice to repent and follow God - Matt 18:15-17). Instead of being bogged down by the disbelief and wrong motives of Simon the Sorcerer, Philip listened to the promptings of God and immediately followed God's next assignment (Acts 8:26-30).
We too can learn a valuable lesson from this humble Christ follower. Philip didn't let his "failures" or the failures of others hinder his effectiveness for God. He listened for what God was calling him to do and he simply obeyed. People under you will not always make the right choice. They may turn their back on God, preferring sin to eternal life. Follow Philip's lead and remember, that your responsibility is you... are you obeying the voice of the Lord? They keep at it and leave the rest to Him!