I received a phone call from a bereaved mother of an eighteen-year-old son. After graduating from high school he had enthusiastically prepared for the ministry. She said he had often set an example for his peers, showing them how to behave as the Lord would want them to. He had told his mother his graduation would come and go quickly, that his remaining time with her would be short and they should treasure it. She had not realized how true his words were. Two weeks after his graduation, in an early-morning drive home from a friend's house, he was killed by a drunk driver. His mother now understood with a broken heart that the ministry he had prepared for was of a higher order—service to our Heavenly Father and to his children in the spirit world. A few months later, the mother learned that the man who had killed her son was seen clutching a Bible in his cell, crying in grief. It seemed God used the return of her son to Him to fill another purpose for Him as well.
Even in our finite awareness we can see how the young man completed his mission in his last few weeks. His spirit was in tune with God's as he prepared himself for his transfer into the spirit world. Then, being in tune, he helped prepare his mother for his departure. And, in giving of his life, he gave of himself two-fold. First, he gave himself back to his Heavenly Father, and two, he helped bring a soul, the drunken man, to his knees in humility before his Creator. Even as Christ gave of himself that others might live, this young man blessed another in his final moments on earth. We are entering a period of difficult but wonderful changes soon to take place in the world. During this time God will call home many elite spirits—such as this young man—to better serve us from there.
Here's a letter illustrating that we may never know who we are called to help in this life:

For many years I have struggled with low self-esteem. While I have made a lot of progress from time to time, I have episodes where I still feel very unlovable. One day, in terrible emotional pain I cried out to God in prayer. I asked him to take this cross from me and to help me to love myself. Prior to this cry for help, I had been invited to the wedding of a person I knew from high school We hadn't been real close in recent years, so I kind of wondered why I had been invited. I had a feeling, though, that there was a reason I should go. Well, that reason appeared in the form of two people who, quite out of the blue, shared with me the reasons why they felt I was a wonderful person. I was deeply touched by their comments, particularly from a person I had hardly seen or spoken to in twelve years. Suddenly I remembered my prayer! I truly believe God used these people as his "conduits." He spoke through them to remind me of my worth as a person and of his deep, abiding love for me. What is even more amazing is that he had all this planned out for me before I even asked for his help.

Every encounter we have, even if brief and seemingly unimportant, may have more significance than we know. A brief encounter may begin a greater ripple that reaches its intended purpose years later. Everyone who comes into our lives may be part of our mission, and we, a part of theirs. Understanding this can gives meaning to the common events of life. By being positive and helpful towards others, even in casual moments, we can make the most of our time on earth.
Occasionally we find people who seem to know the chief purposes for their lives. Some seem to know from childhood. Others discover it later. Here's a letter from a high school junior who knows her mission is to be an actress:

It makes me happy just thinking about it. I pray to God with all my heart and soul for his guidance to assist me in making people happy in my own little way. Nothing has happened yet, but I have a hopeful feeling that something is going to. Deep down I know my prayers are being answered.

She may be right. One way to discern if we are on the correct path is that it brings us great joy and fulfillment. This is how one third-grade teacher in a Catholic school came to realize the nature of her mission:

I truly believe that my mission on earth is teaching the young children about the path they need to follow to be with Jesus, how they need to treat others kindly and do good deeds for others, and how we need to love others with all of our hearts. I couldn't imagine living on this earth without teaching children about Jesus and God and the Holy Spirit. The gleam in the eyes of the children I teach is the reason for my mission. Carrying on the message of God to future generations is my gift to God.