Life's too short
Response to a request to do something that seems too petty to waste valuable time on.
We feel as though we are busy these days, but that's not new. This response goes back in print form to at least the late 19th century, and in people's minds probably much further. In May 1877, The Morning Oregonian included a story with this opinion:
"Oh I say, drawled Gerard; 'life's too short to be wasted talking about a woman. Let's go and get some beer."
In 1975, the English writer Shirley Conran published the book Superwoman, aimed at busy women, and coined the phrase 'Life is too short to stuff a mushroom'.
People seem to have got even busier since and 'life is too short to ...' has become just 'life's too short'. Note the apostrophe. Perhaps now 'life's to short to type is'?