This verse was God's command to Joshua after Moses' death, who had been Moses' personal assistant for 40 years. God commanded him to be strong and courageous, not fearful or discouraged, because God is with him wherever he is. What a powerful promise, especially when it comes directly from God! Joshua trusted God to guide him and fulfill His promises, even though the task seemed impossible and extremely dangerous. And, of course, God did and will always do. Joshua didn't conquer the Promised Land with his physical strength; he did it with the strength of God and with God Himself.
Put your heart and faith in the Lord when you feel that your own abilities are not sufficient, obey God's command, and seek His guidance in your challenges. God is with you wherever you go!

Dear Heavenly Father, Thank You for letting me know that You are always with me. There is nothing I need to be afraid of with Your strength; there is nothing I can’t accomplish with Your wisdom. Empower me to be strong and courageous and seek Your guidance in everything I do. In all my problems in life, help me rely on You. 
In Jesus’s name I pray. Amen.