Not only does God's work in us (sanctification) help his work through us (mission), but it works the other way too. Engaging in God's mission can jumpstart our sanctification as well.
In this brief video, pastor Darrin Patrick explains the importance of living the Christian life among the lost for our own sanctification. Sometimes we don't see how much we need Jesus, he says, until we're deeply involved with people who don't know him. There's something about being around broken people that helps you draw near to God.