Every time I exercise, I feel my muscles getting stronger.

The strengthening does not happen while you are doing it. What happens then is a request, filed. The answer comes later, mostly while you are asleep and thinking about nothing at all.

So the feeling in the moment is not the evidence, and its absence is not evidence either. Some of the most useful sessions feel like very little.

The proof turns up sideways, weeks on, in a supermarket car park — two heavy bags carried the whole way to the door without swapping hands, and no memory of having decided not to.