Jeff Bezos explains why the first thing to do before starting a company is write a business plan

That blank sheet of paper stage is one of the hardest stages. And one of the reasons it's hard is because at that stage, there's nobody counting on you but yourself. It's really just you. And you can quit anytime. Nobody's going to care. And so you set about doing the simple things first. So you want to start a company? Well, the first thing you do is you should write a business plan. And so I did that. I wrote about a 3:30 page business plan. The business plan won't survive its first encounters with reality. It will always be different. The reality will never be the plan. But the discipline of writing the plan forces you to think through some of the issues and to get sort of mentally comfortable in the space. You start to understand, if you push on this knob, this will move over here and so on. That's the first step.