There's a bible verse I've stumbled upon that says, "the joy of the Lord is my strength." I remembered it because I didn't get it. I didn't understand stand how joy can give strength and I didn't get how you knew if God was joyful. After a while I was playing sports and having a hard time, the Bible verse came into my mind and I just kept repeating it over and over. I honestly did feel stronger when I just focused on the joy of the Lord being my strength. Now I'll repeat this verse to myself whenever I'm doing physical activity to remind myself where strength comes from. God's joy comes when we love Him and do what He tells us to. We should get our strength from God and try not trust ourselves too much because compared to God we are so incredibly weak. We aren't strong enough to go through life by ourselves, we need God's strength to get through. He is the one who created more galaxies than grains of sand on all the beaches in the world, He has enough strength to get you through life if you will just rely on Him.