Human beings often decide to dedicate themselves to the service of the Lord only when they have lost or spoiled whatever they once possessed and are no longer capable of doing anything useful with their lives. The only trouble is that the Lord does not need invalids or toothless, doddering old folk; He needs young, vigorous, competent people.
But most young people are primarily concerned with their pleasure. They say, ‘I intend to enjoy life while I am young!’ Getting them to devote time and energy to a divine work is out of the question. It is when they have spent and wasted everything and are decrepit, riddled with rheumatism, and paralyzed or senile that they turn to the Lord saying, ‘Lord, do you need me? I have come to serve you.’ But by then, they have lost everything – their health and strength, hair, and teeth. They have nothing left, and yet that is when they want the Lord to accept them. And the Lord looks at these heaps of scrap-iron and scratches His head; even He can see no way to use them. Assuredly, if you want to serve the Lord one day, you have to start thinking about it when you are still young. 

Oraam Mikhael Aivanhov