In business, as in life, it's crucial to view an unexpected turn not as an obstacle but as a chance to learn, writes Paul Buchheit (paulbuchheit.blogspot.com), co-founder of FriendFeed and the creator of Gmail.

Planning in itself is not a bad thing, but picking a single plan and obsessively sticking to it doesn't allow for much serendipity. The world is very complicated, and we humans are very stupid, so it's good to be flexible and open minded about things. Instead of having one plan, have one thousand plans, and revise them as necessary.