Meditation is a word that can mean a lot of things. And of course not all of them are Christian. But it can mean a style of Christian prayer. One of the many ways to pray is to repeat simple, basic, prayers — often. It doesn't have to be as repetitive as a "mantra", though sometimes praying repetitively can help emphasise something that's important.

Charles Spurgeon, one of the most respected preachers of all time, sometimes used to pray repetitively. He would repeat, "I believe in the Holy Spirit, I believe in the Holy Spirit, I believe in the Holy Spirit...", before preaching (and perhaps at other times, I'm still learning about him).

You can pray anywhere. And if you pray outside, sitting on a mountaintop, you can pray in any style. It doesn't have to be repetitive like a mantra or a "meditation".