Another favorite pastime was digging a tunnel under his home; he attributed the secret of his success to “visits by elves” while he worked in the tunnel: “While I’m digging in the tunnel, the elves will often come to me with solutions to my problem.”
Wikipedia cited a rather entertaining Time article as a citation for this.
My wife wanted to go mining for her birthday. We’re sitting in a hotel five hours from home right now after a lovely Day swinging picks and with a bucket of rock to show for it.