When I worked on Riker's Island, I didn't so much pay attention to the people who didn't get it. When I recently had a meditation at a staff meeting, I kept it moving when some people decided not to do it. Some people had a negative experience in the past, and I told them they didn't have to do it.
I've always thought meditation and mindfulness are 100% pure goodness. But when I think about, I often find meditation harrowing. I have difficulty with negatvie content that comes up, from wincing at social faux pas, to the low light reel of my life, my low points in a kind of montage that proves how horrible I really am. There can be a shaming twist. For whatever reason, I struggle with constructing a positive view of myself, at times, and in meditation I usually work on conquering that problem; I also have more bold face reflections on my mistakes, which I see as positive. Usually I'm better defended. At times I feel I can see more clearly how to take a more pure tack. I see a goal and I take a direction towards it and sometimes I get waylaid. I experience that mostly as a positive thing to notice, even if it's sort of mistake oriented.