Many people, even Christians, take the act of honoring God and giving Him thanks for granted. We're grateful for the forgiveness He's given us, but the idea that we don't have to earn our salvation creeps over into the other parts of our reasoning, causing us to wrongly think that we therefore don't owe God anything. This belief is not just false, but dangerous, as Romans 1:21 teaches us that even those who know God can become futile in their reasonings (our minds) and have their senseless hearts darkened. This can happen if our minds and hearts aren't honoring Him and giving Him thanks.
Nearly every Biblical scholar will agree that the purpose of your life is to glorify God and enjoy Him forever. You are meant to be a jewel in His crown, a spotlight pointed at Him, a fan in the audience screaming His name. It's what you were created for and the reason you were saved. But too many consider what God has done as just His duty, thanking Him and then going back to our self-centered lives, like we might walk out of the hospital that healed us and never look back.
God didn't need to make us, but He chose to. When we rebelled, God should have smitten us out of existence, but instead He chose to send His son to die in our place, that we might have our relationship with Him restored. Nothing we have been given has been owed or earned, and because of that, He deserves our forever honor and thanks. Your mind and heart depend on it!