[ksaj]

I think people who don't exercise don't realize that this is even a thing. A bit of Dunning-Kruger effect.

What I notice is that if I haven't been to the gym for a while, my brain becomes progressively resistant to effort. Since I have ADHD (diagnosed in childhood, not adult self-application of a wiki page on the subject), it is probably more pronounced than for a lot of others. But it is a very noticeable effect that provides incentive to not have prolonged pauses.