When Saul tried to convince David that he could not defeat Goliath; David simply began to list his past victories against Lions and Bears and how God had delivered him. This point is very important; even God told the people of Israel to write things in books for memory (Exodus 17:14). Joshua told him to build Monuments (Joshua 4: 7). This teaches us that it is important to remember the victories that God has given you; these will give you encouragement and as I told you before it may have been your training.