I wish I could worship the Lord with 100% sincerity. I am grieved that I am so self-focused, so many times, when I am worshiping the Lord. I'm thinking mostly of when I gather with my local church to worship, pray, and hear the Word of God. I also privately am very often thinking more about myself than the Lord.
And yet, I do worship my Father, and the Lord Jesus Christ, with my heart at times. It's when His grace is there full within my heart, then I am able to praise and worship God, and be less concerned about myself.
Here are some good words from Donald Whitney on worship:
"How can we worship God without worshiping in vain? .... To worship God is to ascribe the proper worth to God, to magnify His worthiness of praise, or better, to approach and address God as He is worthy. As the Holy and Almighty God, the Creator and Sustainer of the Univrese, the Sovereign Judge to whom we must give an account. He is worthy of all the worth and honor we can give Him and infinitely more. .... So worshiping is focusing on and responding to God. ...both the public and private worship of God should be based upon and include so much of the Bible. The Bible reveals God to us so that we may worship Him. ... Worship is the God-centered focus and response of the inner man; it is being preoccupied with God. ... This kind of worship isn't in vain."
And there's the balance we need to worship God. We need to worship in Spirit, that is with the Holy Spirit, and in truth, that is according to the Holy Scriptures.
Here's a few more good words from Donald Whitney:
"Having the Holy Spirit residing within does not guarantee that we will always worship in Spirit and truth, but it does mean we can. To worship God in spirit is to worship from the inside out. It means to be sincere in our acts of worship. No matter how spiritual the song you are singing, no matter how poetic the prayer you are praying, if it isn't sincere then it isn't worship, it's hypocrisy.
The balance to worshiping in spirit is to worship in truth. We are to worship according to the truth of Scripture. We worship God as He is revealed in the Bible, not as we might want Him to be. We worship Him as God of both mercy and justice, of love and wrath, a God who both welcomes into Heaven and condemns into hell. We are to worship in response to truth. If we don't, we worship in vain."