After the death of Moses, Joshua was established as the leader of the tribes of Israel. He was command to do specific things in order to be victorious over the powerful surrounding nations. He was not told to physically and mentally train harder or study the culture and philosophies of the adversaries. He was instructed to keep the Law (Torah instructions, teachings and guidance of God) in his mouth by meditating on it both day and night. To meditate is to say something over and over again while thinking about the content. This action causes whatever you are meditating on to get into the heart (spirit/soul) Joshua 1:5-9