Ask HN: Startups, how do you not lose focus?

You have a great idea. Great! Now let's get building it.

I know I didn't want to handle that so I tried this to make it easier so I wouldn't need to do that but this is giving me a headache so I need to do that to do this which needs to do that and that to do this and this to do that! So much work, so much progress, so much fixing that and not worrying about this to do that.

So, why was I doing all this work in the first place?