There are a couple of things to consider, when attempting to get a perfect score on the meditation, by accumulating no warnings. The first two things are you body/head placement, as noted in the bottom right corner. This both need to be centered, as annotated by the middle green dot, at the bottom right of the screen. You want to make sure the Kinect can see you fully, so that it doesn’t assume your hands are moving, while it’s glitching around. I would do a 3 minute meditation, as there is less room for error and I would turn the sensitivity in the options menu to (lowest). This should net you this achievement.