It involves one's view of God, a view that sees Him as Holy and just and sovereign, and man as His creature. It stands apart from man's religions, and the vast majority of "Christendom," in acknowledging God's absolute right to do with His creation as He sees fit.
It is absolutely theocentric, purposefully and willfully rejecting the impulse to focus upon man, instead acknowledging that the glory of God's grace is worthy to be praised for all eternity. To be Reformed means you believe in a Savior worthy of worship, One who actually saves, not one who just does His best.
You believe the Gospel is Trinitarian, holy, lofty, awe-inspiring and worthy of the entirety of your life and being. You not only accept the five points, you accept the consistent exegesis and hermeneutics, let alone the view of an inspired, authoritative, consistent, sufficient Word from God, that leads to those five points. And as a result, your view of God, yourself, church, worship, and the world, is inalterably changed.
To be Reformed is to worship God in a way the world just doesn't get, and which evangelicalism as a whole doesn't get, either. You long for the Word, you long to hear His truth proclaimed and honored, and you find anything that detracts from the glory of His truth reprehensible.
You see God's grand decree in His Triune self-glorification from creation to consummation and your heart is drawn out in worship and adoration and awe as a result. That is what it means to be Reformed.