When we come to God in worship, He wants us to be sincere. He isn't interested in lip service. If we are asking Him to change our lives, then we must be willing to change ourselves. We confess our sins and secrets to Christ, knowing that He already knows them, and we repent and turn away from those sins. We worship Him with reverence, recognizing that Christ is holy and above all other things in our lives. This is worshiping in truth.
To worship in spirit, means to worship in the spirit of love, since God is love. We must recognize that God's spirit is the Holy Spirit who can dwell inside us and His love can blossom in us and from us. In order to worship Him in spirit, we must worship Him in all that we do. It's more than just lifting our hands up to Heaven and bowing our knees to the ground. This is only where it begins. Worshiping in spirit is going to work in His name, caring and helping others in His name, handling difficult people in His name, paying our bills in His name, stepping out in faith and trying new things in His name. Worshiping in spirit is part of everything we do and say. It's allowing God's Holy Spirit and love to dwell in us and from us so others will feel His love and the warmth of His light.
When we worship in spirit and truth, we are walking in the perfect love of Christ and our lives become witnesses to others without us ever having to open our mouths and preach a sermon.