A person could begin their life very nagative but ending it very positive. Jacob is a good example, he started his life as a deceiver but ended it as a prophet and priest. 

When Jacob began his life he prosuaded his brother to sell him his birthright for a bowl of food although he could have given him freely. He then deceived his father and stole his brother's blessings, which belonged to him as the firstborn son. This evil cause him to run away from home for twenty years to save his life. During that period he suffered greatly at the hands of his uncle and cousins. Through those experiences God trained him to become a better person. Later on he lost his beloved son, Joseph, for over twenty years during which time he suffered again greatly. Famine finally caused him to go to Egypt to live the rest of his life. 

By that time he had developed into both a prophet and a priest. As a priest he blessed Pharaoah, regarded as possiblely, the greatest leader on earth at that time. By blessing Pharaoah he demonstrated that he was greater than Pharaoah, because the bible says, in Hebrews 7:7 that, as a rule, "The lesser person is blessed by the greater."  As a prophet he prophesied over his twelve sons, predicting what would happen to their respective tribes. 

What we have seen is that Jacobs past did not determine his future. He started badly but ended his life as a great man of God. The principle is, your past does not determine your future. Therefore, no matter how bad your life has been you can end your life as a great person of God. But you must go through the process that God has ordained to train you to become great. To go through your training you must learn from your experiences and pass your tests. PASS YOUR TEST!!!