It's hard to focus when you're a starting a company. It is easier to say yes than to say no. Saying no will give you the feeling that you turned down an opportunity. Saying yes will give you the feeling that you're making progress. But it's important to distinguish being active and making progress. Yes helps you stay active. No frees up time and ressources to allow you to make progress. Anyways, the following tweet made me laugh. I think it is a nice way of highlighting the importance  of staying focused on a few things when you're just starting out: