Knowing yourself – what you stand for, what you want to achieve, how you like things done, what you want to avoid – is important mainly because it saves you from the frustration of not being able to have it all.
You can have control and you can have agility. You can’t have them both.
You can have family time and you can have a glorious career. You can’t have them both.
You can have independence and you can have stability. You can’t have them both.
When you know yourself, you know what matter, and letting go of things is just easier.
Note: of course, there are exceptions. Some people can have one and the other. But exceptions are rare, and betting on them is often conducive to further frustration.