I ran across a disturbing bit of research a few months ago. According to the research the two likeliest groups in our society to commit suicide are: 1) Men over 65, and, 2) teens. It is an odd statistic that makes me ponder "why these two groups?" Here's what I think. American culture values productivity above all else. This is seen in our status symbols of what money buys -- big house, big car, lots of toys, freedom to travel, etc. But for some odd reason men over 65 are told they cannot be productive anymore (we call this retirement -- taking their leisure, etc) and teenagers are not yet allowed to be productive according to the standards of our culture. Now, I understand the importance of child labor laws and all of that and, frankly, think "making money" is a pathetic lowering of what productivity could be -- perhaps we need a better definition of productivity.
Look at the Bible. Abraham was 75 when he was called. Moses was 80 when he was sent back to Egypt. Jesus was roughly 30 when he started his public ministry and there are stories of men and women making a difference and answering the call of God well into their so called golden years. But take it the other way: Jeremiah was called in his early teens. Timothy was a young man (so young that Paul has to remind him not to allow others to despise him because of his youth). Mary, Jesus mother, was likely a young teen when found out she was chosen to bear the Son of God. The Bible gives no such age boundaries for service and ministry.
I have often argued, usually to no avail, that there is no such thing as retirement from the faith. When we get older there may be different forms of ministry and mission our work might take but the truth is if we have moved to the sidelines, spiritual and missionally, in our retirement years we have moved into unfaithfulness. The other extreme is equally important. The Church needs to recognize and call forth the gifts of our youth and encourage, allow and deploy them in their service to God.
There is no too young and no too old to follow Jesus or to make a difference in this world for Jesus sake.