Having a good strategy and being disciplined about following it is NOT about saying yes to the good choices and no to the bad. When you are a startup, you have tons of choices, lots of room to pivot, and lots of things you can spend precious resources on. The key is to learn to say "no" to really good things, choices that almost kill you that you are saying 'no' to them - but you need to do so to keep focus and resources not the 1 or 2 things that you DO say yes to. Its easy to say no to bad choices. What is tough is saying no to good choices. But if you are to succeed in managing or leading a start-up, learning to say No to good things is just what you must learn to do.