However you feel about the debate about whether you can do everything, should do everything, or if everything can be done at once, there are times when slowing down can be enjoyable. Or essential. It's a bit like spinning round very fast in circles, though (I can't be the only one who used to love spinning on office chairs as a kid... or when nobody else was around when older...) - once you stop, it feels like the rest of the world is still whirling faster than ever.
This poster made me smile when I first saw it*... I don't take it as an admission of defeat, but as a statement of sanity preservation for occasional use.
The way I look at it, it's not about telling yourself you can't do seven impossible things before breakfast if you so choose, but perhaps about telling other people. If it was good for everybody to know what you could really get up to, why does Superman have an alter ego...?
* Yep, it's another exception to the Keep Calm rule.