Healthy Pastoral Ambition?

At times, I wonder about ambition as a pastor in the United Methodist Church. On one hand, I am appointed and sent to serve at a local church by the bishop. It can be unhealthy to always "live in the next appointment" - looking forward to what might be. On the other hand, God has hopes and dreams for our life that can be made known to us. What would you say is healthy and faithful pastoral ambition?