In the Zen tradition, meditation is “just sitting.” In the Catholic tradition, prayer is “raising the mind and heart to God.” The Catholic definition is good in that it does not go into detail specifying any particular methods of prayer. The Zen is even less definite. Although it does say sitting, any straight spine posture is okay.
For me, my morning half hour of meditation/prayer has become just assuming a cross legged posture, and expressing an intention to be present to God. Mind and heart?! My mind remains in the present moment perhaps for one minute out of the thirty. My heart at least makes the intention before it too wanders elsewhere. Only my body remains where it is. Most of my prayer/meditation is just “raising the body to God.” It sitting, but not “just sitting.”