Per a sibling, it is Chesterton, from his work
What's Wrong with the World:
* https://www.gutenberg.org/files/1717/1717-h/1717-h.htm
An explanation:
> Chesterton consistently defended the amateur against the professional, or the “generalist” against the specialist, especially when it came to “the things worth doing.” There are things like playing the organ or discovering the North Pole, or being Astronomer Royal, which we do not want a person to do at all unless he does them well. But those are not the most important things in life. When it comes to writing one’s own love letters and blowing one’s own nose, “these things we want a man to do for himself, even if he does them badly.” This, argues Chesterton (in Orthodoxy) is “the democratic faith: that the most terribly important things must be left to ordinary men themselves – the mating of the sexes, the rearing of the young, the laws of the state.”
[…]
> In What’s Wrong with the World, Chesterton foresaw the dilemma of daycare and the working mother, that children would end up being raised by “professionals” rather than by “amateurs.” And here we must understand “amateur” in its truest and most literal meaning. An amateur is someone who does something out of love, not for money. She does what she does not because she is going to be paid for her services and not because she is the most highly skilled, but because she wants to do it. And she does “the things worth doing,” which are the things closest and most sacred to all of humanity – nurturing a baby, teaching a child the first things, and, in fact, all things.
> The line, “if a thing is worth doing, it is worth doing badly,” is not an excuse for poor efforts. It is perhaps an excuse for poor results. But our society is plagued by wanting good results with no efforts (or rather, with someone else’s efforts). We hire someone else to work for us, to play for us (that is, to entertain us), to think for us, and to raise our children for us. We have left “the things worth doing” to others, on the poor excuse that others might be able to do them better.
> Finally, and less heavily, we should also point out that the phrase is a defense of hobbies. […]
* https://www.chesterton.org/a-thing-worth-doing/