There is a great song by Trevor Thomson that has a refrain that can turn into a kind of mantra, and a darn good one, too - "Christ in Me Arise".
"Christ in me arise and dispel all the darkness. Christ in me arise with your power and your strength. Christ in me pour out your blessing and healing. Christ in me arise and I will rise in You."
(The melody is in the "music" section of this website. It's a wonderful tune.)
Now, as a meditator, I do not use mantras, per se. But there are lots of way to meditate. Some people use mantras and they can be very helpful (a mantra is a phrase you use to focus your mind while meditating). And just because I don't use one doesn't mean things like that chorus don't pop into my head when I meditate.
In fact, when I go on silent retreats of 8-10 days it usually takes about 2-3 days for the music to stop playing in my head. A few years ago on a retreat that chorus was playing internally for a couple of days. And it is not like I was trying to make it happen. Or not happen.
Either way. Isn't that a beautiful chorus/mantra to have in your head if you are praying or meditating or walking around or sitting or anything?
Christ in me arise. Yes, indeed!
Peace,
Paul