Wipro's Azim Premji carries 5x7 index cards and writes down all the promises he has made, according to a book. He then files these cards in a way that makes them easy to recall when needed. The book, 'The Art of Bitfulness: Keeping Calm in the Digital World', has been authored by Tanuj Bhojwani and Infosys Co-founder Nandan Nilekani.