Do you not know? Have you not heard? The Lord is the everlasting God, the Creator of the ends of the earth. He will not grow tired or weary, and his understanding no one can fathom. He gives strength to the weary and increases the power of the weak. Even youths grow tired and weary, and young men stumble and fall; but those who hope in the Lord will renew their strength. They will soar on wings like eagles; they will run and not grow weary, they will walk and not be faint. - Isaiah 40:28-31
It is normal to be weary and to tire. Every form of human strength must of necessity, expend itself. It's kinda like fueling your car for a journey. After a long drive, you'll run out of gas if you do not top up on it. In the same vein, all strength apart from God's is depletable and exhaustible. Only God's divine strength is infinite and inexhaustible. This is why the Bible says, those who wait on the Lord will renew their strength. Your communion with God is what gives you this advantage. Renewed strength is the rejuvenated strength that God provides when you commune with Him. Have you prayed today? Have you spoken to the Father? He is always ready to listen to you and talk to you.