So St. Paul's advice in 1 Thessalonians 5:20-21 struck a cord with me: "don't despise inspired messages, but do test everything -- hold on to what is good." That speaks to my struggles pretty plainly. When God says step out in faith I need to get with the program and not waste time and energy second guessing. But, on the other hand, I am both given permission AND directed to test everything.
How does that work? First of all, God will never tell you to be abusive or steal or murder or slander or embezzle. I believe it is possible for God to call me to civil disobedience when the law of the land contradicts my understanding of God's laws but that is rare and not really the point here. If you are being called to break the Ten Commandments you can be sure you are off track.
Secondly, it is natural to have a "say what???" response to God calling you to step out in faith. But just because you HATE speaking in public does not mean that God will not prod you to ask a question or share an observation in Bible class. Being reluctant is OK as a starting point and asking God to confirm your understanding of where you are being lead is good. I will offer this advice. If you say, "God, if I am truly understanding what You want me to do, please send someone to affirm my understanding." you might want to write down what exactly you asked God to do so that when the person you like least in the world shows up and says they have been praying for you and feel God has given them a Bible verse that might be helpful in your discernment process, you can resist the temptation to say, "Oh, but God, if You wanted to get a message to me I just know you would have NOT have sent that person so I'll just ignore that!" (Yes I've done that foolish thing too!) If you need helping finding your way to do what you believe you are called to do, you are wholly welcome to ask God to help with that too.
And then St. Paul adds, "Hold on to what is good." So often we allow our self-talk and talk within our ministry community to slip into a litany of frustration. And I believe that here St. Paul reminds us to affirm God's commitment to our highest good, lift one another up, say out loud, "God is with us and we will proceed with humility and prayer and confidence in God's power and love."
Hold on to the good with the help of the Spirit of God so that there is ever less room for the bad we are so inclined to cling to because it is familiar.