And David was greatly distressed; for the people spake of stoning him, because the soul of all the people was grieved, every man for his sons and for his daughters: but David encouraged himself in the LORD his God. 1 Samuel 30:6 KJV
This was after David and the Israelites had suffered an attack while fighting at Ziklag. The Israelites were mad at David and wanted to kill David because he had let their wives be stolen and their area was burned and destroyed. David was very stressed out and upset because his people wanted to kill him, but, he didn't just have a pity party, David encouraged himself in the Lord.
The Hebrew word used for encouraged is transliterated Chazaq. That means to encourage, or to strengthen, or to become strong. So, when David was distressed, beat down, broke down, and worn out, he turned to the LORD for strength. Sometimes, a part of strengthening is resting and receiving power .This is very true in God's realm.
Acts 1:8 says that we receive power when God's spirit comes upon us. We need power. I know I need power. We gain power and strength when the Spirit of God comes upon us. Or, when we are in the Spirit of God. Prayer is a way to get in the Spirit. We are to always make prayer and supplication in the Spirit of God according to Ephesians 6:18. Ephesians 6 talks about the armour of God and the things needed for Spiritual Warfare.
My personal belief is that in all of the weapons, they are all defensive- the helmet of salvation, the breastplate of righteousness, etc. The Bible, the sword of the Spirit, is offensive. It is how we counter attack the enemy. And, that praying is our strength... it is how we gajn strength. I know with me personally praying before school starts makes a world of a difference from when I either don't pray before school or only get a small minute or two to pray. Spiritually, I feel stronger when I pray... Praying being strengthened by the Spirit of God or resting in God's Spirit.
For with stammering lips and another tongue will he speak to this people. To whom he said, This is the rest wherewith ye may cause the weary to rest; and this is the refreshing: yet they would not hear. Isaiah 28:11-12 KJV The stammering lips and new tongue, happen in Acts 2:1-4. Many people try to ignore that part of the Bible, like it says, they won't hear. God told us he would provide a rest, and shared what the rest would be in Isaiah 28. God provided a means for rest. We choose whether we enter God's rest or not. This is the refreshing God promised us.
When you feel worn out, beat down, or just tired, remember, God will be here when we need help. God is present when we need him. God is our refuge. Psalm 46:1 says God is our refuge and strength, a very present help in trouble.