"Youth is the planting time of full age." We can determine the tree by the shoot springing up and the fruit by the early bud. You can determine the type of day it will be by the early morning clouds, unless you live in Texas where the weather can change by the moment! In the same way the type of person you will be as an adult can be determined by your character now as a young man.
Do not assume you can put off Jesus until you are an old man. Do not give the world, the devil, and your selfish lusts the most productive years of your life. You should not put off deciding to follow Jesus now rather than later, when the Bible warns that we are not guaranteed tomorrow and that every man should decide to follow Jesus today. As long as you have breath in your lungs there is an opportunity to repent and turn to Jesus, whether you be young or old. But why wait? the longer you wait the more stronger the roots of sin will have wrapped around your heart.
It is a true saying of good Archbishop Leighton: “The way of sin is down hill; a man cannot stop when he would.” the older you get the stronger become the habits. Habits become chains that increase in strength the oldernyou get. Sins that are allowed in your heart while you are young will not be easily removed when you are older. A young boy can bend a sampling quite easily , but 100 men cannot uproot an aged tree. Jeremiah, the old testament prophet rightly said, "Can the Cushite (a black-man) change his skin, or a leopard his spots? If so, you might be able to do what is good, you who are instructed in evil." It is hard to give up habits started when you are young, not impossible, but hard. So it is with habits: the older the stronger—the longer they have held possession, the harder they will be to cast out. They grow with our growth, and strengthen with our strength. Every fresh act of sin lessens fear and remorse, hardens our hearts, blunts the edge of our conscience, and increases our evil desire.
Habits, good and bad are strengthening in your heart every year you get older. Those sinful habits will pull you further and further away from Jesus with each year. Every year you remain away from Jesus the gorge will become deeper and broader, the gateway will become higher and heavier to open. Submit to Jesus now and do not put it off another moment.
(A modern re-telling of Ryle's "Thoughts for Young Men)