Going on my own anecdotal experience, I think there is substantial marginal benefit to cardiovascular exercise even at the level of 4+ hours a day of said exercise.
For a while I've been doing 4 or 5 hours a day of cycling and it seems to have weird cognitive effects similar to those of caffeine. While exercising I seem to sometimes go into some sort of trance state where I'm pretty excited and can do lots of work (at the same time as the cycling) pretty quickly without it feeling like actual work. I can listen to the same dance track 30 times without becoming bored of it. I think this might be due to 'runner's high', or due to increased blood flow to the brain.
Often, there are questions you want to know the answers to. You want other people's opinions, because knowing the answer isn't worth the time you'd have to spend to find it, or you're unsure whether your answer is right.
LW seems like a good place to ask these questions because the people here are pretty rational. So, in this thread: You post a top-level comment with some question. Other people reply to your comment with their answers. You upvote answers that you agree with and questions whose answers you'd like to know.
A few (mostly obvious) guidelines:
For questions:
For answers:
This thread is primarily for getting the hivemind's opinions on things, not for debating probabilities of propositions. Debating is also okay, though, especially since it will help question-posters to make up their minds.
Don't be too squeamish about breaking the question-answer format.
This is a followup to my comment in the open thread.