"Every place on which the sole of your foot treads" was the promise God gave Joshua. That promise brought with it the unspoken assumption that Joshua, too, would be a "walker". He was about to begin his walk with God in an entirely new way.
After Moses' death, his faithful assistant Joshua was appointed by God as the next leader of the wandering children of Israel. They were about to enter the Promised Land and Joshua had many difficult battles ahead. When God called him, Joshua had a pretty good idea of the task ahead of him, and he must have been terribly frightened of what was to come. God told Joshua three times in these six verses, "Be strong and courageous." Courage and strength in his actions and leadership were not automatic. They were a choice Joshua would have to make on a daily basis and we would do well to make that same choice today.
What is amazing about these verses is that God gave a very specific "recipe for success". If Joshua did what God said, he would prosper. These instructions are worth understanding.
1) Be very careful to obey all the law. He was not to pick and choose what best suited him. He was to obey everything God said.
2) Meditate on the law day and night. Don't let it depart from your mouth. Joshua could not obey the law if he didn't know the law. Studying God's word was like insurance against failure.
These two very simple rules would be just as effective in our lives as they were in Joshua's. Study Scripture so you know what God says, then do it. Every single time. How simple is that? The most amazing thing about this whole formula for success is that it comes with an astounding promise from God.
"I will be with you; I will not fail you or forsake you...the Lord your God is with you wherever you go."
If that doesn't make you want to study and obey, I can't imagine what would!