One thing that often disrupts momentum and really shouldn't is competitors.

If someone is choosing between joining McKinsey or your startup it's very unlikely they're going to work out at the startup.

You only get points when you make something the market wants. So if you work really hard on the wrong things, no one will care.

At YC we have this public phrase, and it's relentlessly resourceful.

Even though plans themselves are worthless, the exercise of planning is very valuable and totally missing in most startups today.

Most things are not as risky as they seem.

It's better to have no cofounder than to have a bad cofounder, but it's still bad to be a solo founder.