True worship engages every part of our being – our mind, our bodies, and our will, but especially our heart. Stephen Charnock concerning the importance of engaging our heart in worship: No sincerity = No worship.
Without the heart it is no worship; it is a stage play; an acting a part without being that person really which is acted by us: a hypocrite, in the notion of the word, is a stage-player. We may as well say a man may believe with his body, as worship God only with his body . . . We may be truly said to worship God, though we want (lack) perfection; but we cannot be said to worship him, if we want (lack) sincerity.