I can only speak for myself, but the only thing that boosts my concentration is to buckle down and concentrate - which rules out most of the above. It usually t

I can only speak for myself, but the only thing that boosts my concentration is to buckle down and concentrate - which rules out most of the above. It usually takes a couple of hours before the effect is noticeable. (I'm not claiming to be good at it, but I have learned what works for me.) The other thing is to notice when I am no longer able to concentrate any more, as it is no longer productive to keep going. When that happens, any of the above might be helpful, but that list is missing the most important one: get enough sleep. Your list is mostly of solitary (or not explicitly social) activities, but socializing is also helpful for me.