Marc Hedlund, a co-founder of personal finance site Wesable, has some nice advice on what to ignore when you're running a start-up:
"Running a startup is a great way to learn how to, and how not to, ignore the right things. You should mostly ignore your competitors and mostly ignore the minor ups and downs that feel fantastic or terrible when they happen. You should pay a huge amount of attention to the unbiased people who are actually using your product or service -- not friends or enemies or professional commentators, but people who show up through a search, sign up and give it a try. Ignore everything that makes you miserable, pay tons of attention to everything that makes you happy and productive. Ask someone for help every day. And call your friends, you nincompoop."