I think I remember that when I read The Alchemist by Paulo Coelho, there was a story in it of the alchemist, who only wanted to make gold. A great sage told him that he would succeed with his ingredients, if only he added one more: unshakable confidence that he would be successful.

I may have just found the lesson that is common to insomnia, sex drive, and the above story:

‘Worrying about it doesn’t help.’