I think when we ask this question we tend to make it about ourselves, which can set us off on the wrong path to begin with.
God calls us to be 'others centered' and to love God with all our heart, soul, mind and strength.... and it's to have fellowship with Father, Son and Holy Spirit. Without that relationship and fellowship, anything else that we might deem to be our 'purpose' is meaningless.
If you're asking about 'purpose' in terms of a job, career, ministry, having a family, etc.... I don't know if it matters what you do, but rather we are to be in fellowship with Jesus in everything that we do. I believe that God does put a specific call on people's lives for specific things, but not so for everyone.
So- to answer your questions:
1) What do you believe God's purpose for your life to be?
My purpose in life is to Glorify Him, be obedient in His teachings, have fellowship with Him now while also looking forward to the day that I will be with Him forever. It's like having one foot on earth and one foot in heaven. 'What' I do while I do those things doesn't really matter. (I say these things for anyone reading assuming of course that no born again believer would choose a criminal lifestyle.)
2) What transpired in your life that made you realize what it was?
Well... Getting to know Jesus, spending time in His word, in bible study in groups, going to church, praying and receiving answered prayer, journalling is teaching me that my life is all about Jesus. If it weren't for Him I wouldn't have life. It's an ongoing learning and growing... as I tell it to others it is more and more real for me. Before knowing Jesus I can honestly say I constantly wondered what my purpose here on earth was. Knowing what it is gives me peace, and helps me to be still and rest in Him.