Make mistakes of ambition and not mistakes of sloth. Develop the strength to do bold things, not the strength to suffer. (Quoting Machiavelli.)

A lot of stuff feels like work—commenting on HN, tweeting, reading about other companies' funding rounds, grabbing coffee—is not actually work. If you count that as work, think really hard about the value you're creating in your job.

When running a company, Altman made a list of everything he got done at the end of each day. It was remarkable how a day could feel really busy yet produce nothing, while a day that felt only somewhat busy could accomplish 3 or 4 major things.

You build what you measure. If you measure your productivity by the number of meetings you have in a day, you will have a lot of meetings. If you measure yourself by revenue growth, you will probably have fewer meetings.

Strategy is far more valuable than pivot-happy companies would have you believe—but strategy alone has no value. Value gets captured by execution, which is why you can generally tell people what you're working on without NDAs and most patents never matter.

If you believe going to space is the most important project for humanity, work on it. If you can't raise hundreds of millions, go work at SpaceX—joining a great company is a much better plan than starting a mediocre one.

A lot of people feel they should first do something to make money and then do what they care about. Life is short and you only get to work on a small number of companies over a career—it's worth trying to make them count.