When I did it, I had the sensation of being denied breath. Mildly unpleasant, but I think this is what forced present focus and got me out of stress. Not very

When I did it, I had the sensation of being denied breath. Mildly unpleasant, but I think this is what forced present focus and got me out of stress. Not very unpleasant mind you. Same level as seeing how long you can hold your breath, except much less intense.