John 6:38 (NKJV)
Have you ever had the experience of walking into a room and when you got there you didn't remember exactly why you were there? You find yourself unsure of what to do next because you forgot the reason for why you are in the room. Some people say that is just something that happens when people get older, but it can happen to anyone because we can all lose our train of thought or get distracted. No matter how something like this might happen, the issue is about not knowing the purpose for being somewhere, without a purpose you can feel lost.
When Jesus was on the earth He made many statements about what He was doing here and why He was doing it. For example, Jesus said He came to do His Father's will and not His own will (John 6:38), He came to fulfill the Law (Matthew 5:17), to seek and save the lost (Luke 19:10), and to serve others and to give His life as a ransom for many (Mark 10:45). Jesus knew why He was here and what He was here for, the question is if we know why we are here what we are here for. If we don't know what our God given purpose in life is, then our top priority needs to be to find out.
The best way to discover God's purpose for our life is of course to read and study God's Word and to talk to Him in prayer. A great way to learn more about our purpose is to get involved in our local church and by helping others. Our purpose from God does not revolve around ourselves and it will only be seen in relationship to others. God has a plan for each and every person and He has given everyone some gift and ability to use to glorify Him and serve others, our task is to discover this gift and then to make the best use of it as God directs us.