As you enter into prayer, express your intention to love God with all you have (Luke 10.27). I will often improvise on some alluring passage of Scripture that arouses my love, my devotion, my pursuit of the Beloved. Song of Solomon 1.1-4 or 2.8-14 are my preference. These intimate love letters once used between two lovers are, in the history of spirituality, invitations to the divine romance. Express them to God, your Beloved, and let them set your heart aflame.
Obviously, your heart will not always "burn within you"--especially at dawn after you've stumbled out of bed, and perhaps haven't slept well or had your morning coffee. You may have difficulty focusing at the end of a long and troubling day. No matter, you've expressed your intention. That's what matters.
Your body and mind will follow your words eventually. If not today, then after the hundredth time you've mumbled the words. One day you'll speak the words as you have ninety-nine times before, but this time there's a sudden brush of wings, a gentle nudge, a voice that comes to you. You look up and see your Beloved running toward you, and you'll feel yourself rising up with a desire you've not engineered. Love has come for you, unexpected, unforced.
You expressed your intention, then waited. And Grace has come to you; your prayer becomes a dance, or better, a holy bed for lovers.