The source of this is unknown, but if true, is definitely worth thinking about.

“Picasso was sitting at a table outside a Paris cafe. A woman came up to him and asked him to sketch her. He complied. After five minutes he finished. The woman asked what she owed him for the sketch. He said the equivalent $5,000. Aghast the woman said — “but it only took you five minutes!” Picasso replied — “no Madam, it took me my whole life.”