Famous CEOs Who Write Personal Thank You Notes

Each year, Facebook founder and CEO Mark Zuckerberg gives himself a personal discipline challenge. In 2013, it was to meet a new person who doesn't work at Facebook every day. In 2010, he set out to learn Mandarin.

In 2014 Zuckerberg revealed that he is challenging himself to write one thank-you note each day.

In a Bloomberg Businessweek cover story he vowed to write "a well-considered thank-you note every day, via e-mail or handwritten letter." His ...