Joshua was successful because he followed God's instruction to him as recorded in Joshua 1. If we follow those instructions, we too will be successful!
Joshua 1:8,9 This Book of the Law shall not depart from your mouth, but you shall meditate in it day and night, that you may observe to do according to all that is written in it. For then you will make your way prosperous, and then you will have good success. Have I not commanded you? Be strong and of good courage; do not be afraid, nor be dismayed, for the LORD your God is with you wherever you go.
I hope you have found this helpful.