Unable or unwilling?

I was reading this morning Luke chapter one. I was reading about Zechariah, the soon to be father of John the Baptist. Zechariah doubts the power of God and is struck mute until his child is born. The following is Luke 1:8-20

Now while he was serving as priest before God when his division was on duty, 9 according to the custom of the priesthood, he was chosen by lot to enter the temple of the Lord and burn incense. 10 And the whole multitude of the people were praying outside at the hour of incense. 11 And there appeared to him an angel of the Lord standing on the right side of the altar of incense. 12 And Zechariah was troubled when he saw him, and fear fell upon him. 13 But the angel said to him, “Do not be afraid, Zechariah, for your prayer has been heard, and your wife Elizabeth will bear you a son, and you shall call his name John. 14 And you will have joy and gladness, and many will rejoice at his birth, 15 for he will be great before the Lord. And he must not drink wine or strong drink, and he will be filled with the Holy Spirit, even from his mother's womb. 16 And he will turn many of the children of Israel to the Lord their God, 17 and he will go before him in the spirit and power of Elijah, to turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just, to make ready for the Lord a people prepared.”
18 And Zechariah said to the angel, “How shall I know this? For I am an old man, and my wife is advanced in years.” 19 And the angel answered him, “I am Gabriel. I stand in the presence of God, and I was sent to speak to you and to bring you this good news. 20 And behold, you will be silent and unable to speak until the day that these things take place, because you did not believe my words, which will be fulfilled in their time.”

As I read this I wondered how many times I have been struck mute, not by God but by my own doubt. My unbelief. My fear. How many times have I not spoken up because I was scared of what man may think. How many times have my lips remained silent when truth should have been spoken? How could I possibly speak truth, I am just a sinful man. I need to remember that although I am a sinful man, I am a man who was chosen by God for salvation to do His work, by His power, and for His glory. Amen and amen!