You can ask around to find a clairvoyant you can trust or a person who does past life regressions. Authors like Carolyn Myss write about soul contracts, and she believes we can figure it our ourselves. Her book Sacred Contracts may be helpful to you. Sometimes we have intense dreams or experiences which answers this question. Or feel an affinity for what it could be.
Go to a clairvoyant if you find one, and just ask about your life. Try to ask about the person first. They will charge for their time, probably about $50.00 an hour. But that could be enough for you to see if they are good and if you feel you can trust them. Many of them know how to do past life regressions because what you decided to do in this life was decided before you were born into it.