Lesson 1 - There's No Plan

You can't sit there at age 21 or 31 or 41 or even 51 & map your life's trajectory all out. You may think X will lead you to Y will lead you to Z, but it never works that way. The world changes. In a decade, your job might be in some other geography and even your industry might not even exist. And, you'll change too. You might discover a hidden talent.

That doesn't mean you should let random things happen with you, you'd need to make smart choices, based on instrumental reasons or fundamental reasons. This would make you an enlightened pragmatist.