There is a difference between the man and the office into which the Lord has placed him. Whether King Saul was little in his own eyes or not, he was the anointed one of God, placed into his office by God as king of Israel. Whether Timothy was young or not, he was the one called by God and placed into his office as pastor. In the office is the authority of God. On that we rely, not on how we see ourselves or not.
I often find myself, as a pastor, as "little in my own eyes." I know my own shortcomings and failures, weaknesses and struggles. In many ways I still see myself as a "young pastor," even though I have been in the office for 15 years now. It is a struggle for me to see myself as someone who has experience and who others look to for leadership. I still often see myself as a young guy just out of seminary.
These verses remind me that it doesn't matter how I see myself, and that, in fact, satan would very much like me to look at myself instead of at Christ and the office into which He has placed me and given me authority to teach and preach and administer the Sacraments. As it always is, when we take our eyes off Christ, we become filled with doubts and fears. It doesn't matter how old a pastor is - as he is called and ordained into the Office of the Holy Ministry, he speaks with the authority of the office, and as such can have full confidence.
Even Luther, at times, struggled with this, I believe. In those moments he looked at himself, he wondered how he could presume to teach the church; he who was just a little friar. Who was he? Yet when he considered the Office into which he had been put to speak the Word of God, he knew it didn't matter who he was - he had been chosen by God and called and put into that Office to speak this Word, no matter what. And with his eyes off himself and looking to Christ, his confidence was renewed.
I will, no doubt, struggle with this in the future. When I do, I thank God for these words! Did God not put me here? Am I not called and ordained into this office? Then speak and do not fear. It matters not who I am. But "as a called and ordained servant of the Word and by His authority, I therefore . . ."