At first glance it seems like Joshua has very little to worry about - very little need to "Be Strong and Courageous" - in verses 3-5 God had just finished promising Joshua that nobody would be able to stand against Him. He promised Joshua that He would never leave him or abandon Him. But upon further examination - what God did not promise is that it would be easy - He did not promise that people would not try to stand against him - but He did promise Joshua that he would be successful.
God has made these same promises to us.
Romans 8:31 (NLT)
Nothing Can Separate Us from God’s Love
31 What shall we say about such wonderful things as these? If God is for us, who can ever be against us?
Hebrews 13:5–6 (NLT)
5 Don’t love money; be satisfied with what you have. For God has said,
“I will never fail you.
I will never abandon you.”
6 So we can say with confidence,
“The Lord is my helper,
so I will have no fear.
What can mere people do to me?”
Joshua 1:7–8 (NIV)
7 Be strong and very courageous. Be careful to obey all the law my servant Moses gave you; do not turn from it to the right or to the left, that you may be successful wherever you go. 8 Do not let this Book of the Law depart from your mouth; meditate on it day and night, so that you may be careful to do everything written in it. Then you will be prosperous and successful.
Too many people forget the part about being obedient. They want to believe that just because they are Christ followers - everything is going to be handed over to them - but God has said that we will only be prosperous and successful if we obey His word and follow his commands - all of them not just the easy ones.
Unfortunately for the Israelites - when it came time to take the land that God had promised them, many of the tribes gave up and settled for less than God had intended because they found out it was too hard. As a result they never enjoyed the full extent of God's blessing and faced many hardships down the road.
Never give up - never settle for less than God's best - it won't be easy - but it's worth it.