The article allows for breathing and blinking, but has an odd constraint of “don’t move”, which AFAIK will make one fight their own neural system trying to autoregulate arousal. I’m not an expert but in my limited understanding, remaining completely still is not “not doing anything”, it’s very active inhibitory action.

As an experiment, just get in a nice running shower, so your sensory system will get external stimulation. YMMV, but for me three minutes pass quick. I just did that and when I decided to check the time it was almost 5 minutes already.

Real “doing nothing” is just leaving things be, just chilling out and observing whatever is happening without actively participating - and three minutes is a pretty low mark for that, unless we’re talking about fellas with ADHD.