"My son, do not make light of the Lord's discipline and do not lose heart when He rebukes you, because the Lord disciplines those He loves, and He punishes everyone He accepts as a son. Endure hardship as discipline: He is treating you as sons... God disciplines us for our good, that we may share in His holiness... it produces a harvest of righteousness and peace for those who have been trained by it." - Hebrews 12:5-11
When you look at the lives of some of the people that God used in great ways, the majority of them went through one or more times of being in the "wilderness" - a period of trials and difficulties and suffering. In the Bible there are some good examples: Moses spent 40 years in the wilderness, and he came out quite a different person. He came out of the other side of this banishment to the wilderness as a faithful servant of God. Abraham went through a training period of 25 years before God's promise of a son and of being the father of a nation came to be. There was a period of 17 years between the time God proclaimed that David would be the king and the time he actually took the thrown as king. This 17 years was filled with difficult trials, and even fearing for and hiding for his life from King Saul who was trying to kill him. Later in Acts 13:21 God called David "a man after my own heart". Joseph was nearly killed by his brothers and then sold as a slave when he was 17 years old. He went through very difficult times of suffering and heartache, and he remained a slave until he was 30 years old, a "wilderness" period of 13 years. He definitely came out the other side as a different person - he came out as a humble servant of God, a man that God could use to do whatever He wanted.
Our family has gone through alot of "wilderness" time - years of various trials and difficulties - financial difficulties, failures, times of great frustration, cancer, depression, sickness,... Many people give up on their walk with God during this "wilderness" period, which could be a time of punishment/discipline, or it could be a discipline time of training or molding & shaping. These times are very difficult to endure, and in fact too difficult without God's presence and grace. Perhaps you are going through this type of difficulty now. Rest assured that God is in control, and He has a very definite purpose and reason for what you are going through. And He sees the potential and the possibilities of what He can do through you once you get to the other side. You will be a more humble and faithful and appreciative and obedient servant and friend of God that He can use in incredible ways. Stay close to God, your source of victory.
Here are some other verses that may help you: Psalm 66:8-12, John 15:1-5, Malachi 3:2-3, James 1:1-4, John 17:9-11, Romans 8:28-29