Aileen. answered...

This question started my whole spiritual quest, so it is only most appropriate for me to now answer it.

Mormons believe that we were chosen by the Heavenly Father in the spirit world pre-existence to receive a physical body and to come to Earth to our specific mother and father. We agreed, and we essentially are fighting on Heavenly Father's "side" in the war with Lucifer. It is our spiritual "job" in this world to live a certain way, to use our agency to choose between good and evil, in line with the teachings of Jesus Christ, Heavenly Father's only son, whom He sacrificed to allow for our atonement to allow for our spiritual progression.

Mormons believe that while here on Earth, we should learn and live more like our Heavenly Father. This is our spiritual quest which is accomplished through our choices. We marry and build our own family, and by following the Scriptures and living accordingly, we receive access to the Temples where eternal ordinances are performed individually and together as a family.

We can be with our family forever, after death, joined together in Heaven, with Jesus Christ and our Heavenly Father. We have greater peace in this life and eternal joy in the life to come. This is the purpose of our life here.

Before I understood this and became a member of the Church of Jesus Christ of Latter-day Saints, my life was reasonably happy but devoid of purpose. Something was missing. I felt incomplete.

Now, I have peace. My soul is soothed.