"It's easy to look back and say, 'I wish I had done this,' or, 'I wish I hadn't done that.' Do that too much and it becomes habit, and when that happens, when you're constantly dwelling on the past, reaching your future is like the blind man in a dark room looking for a black cat...that isn't there.

Look forward. Refer to the past only for the purpose of learning, but always look forward!" - Tim Hunt, Finisher Freak