If you decide to try working with a mantra start out by spending some time just getting familiar with the words and the sounds of it; work with that level until you feel comfortable saying the words out loud. Then, when you feel familiar with them, start to chant the mantra. As you chant, start to surrender to it; start to merge into it; start to offer up all of your other thoughts as sacrifice to it.
Let's say you're doing your mantra and this thought comes up: " I don't think this is gonna work." Take that thought, and in your imagination, place it on a golden tray, with a silk handkerchief and incense and a candle, and offer it to the mantra. Just keep doing the mantra while you offer your doubt to it. Keep offering up the mantra, and keep offering into the mantra. Offer your doubts, offer your discomforts, offer your boredom, offer your sore throat. Offer. Keep offering. And keep doing the mantra.
— Ram Dass in Paths to God