Fire in my heart

I have this prayer that had been on my heart for about a week now. And it is that God would set my heart on fire. Sometimes I take a step back and look at my life, and my relationship with God and I realize how sinful I am, and how much I fail at being holy. I want my heart to burn with love for him. I can't describe what I want, and how bad I want it. I know that God will answer my prayer in his timing, sometimes its just so hard to wait.