I'm 37. What has been more and more apparent to me is that most people don't know shit about shit. Even experts in their field. For example this forum, which I dearly love: if you share anything you have built, an idea, a counter-argument, you will find someone ready to demolish it and say it is worthless, not to waste your time. It's been done before. Nothing new exists under the sun.

When I was younger, I thought they knew better, so I kept at it and learned. Now it is apparent that most people default to a cynical, negative kind of state. It probably it is a manifestation of our physiological need to conserve energy and not to abandon our comfort zone, a worldview we force onto other people, and many fossilise into without accomplishing much.

So now, at 37, and perhaps more arrogant than before, I have learned never to take a no for an answer from anybody. Never to listen to anyone that says "it's stupid" or "it is impossible." The world and the future depends on reckless people that try to do what no one has dared to do before. You can still be humble and learn, but you'll find the true Masters are the most optimistic and enthusiastic ones. Keen to help and keen to share. The nay-sayers can be safely and absolutely ignored without exception.

You have spent your 20s mostly learning and following orders. In your 30s, it is time to carve your own path, however crazy or silly it might be, as long as you feel that deep pull towards it you cannot say no to. As other said, you have at least 20 more years to achieve the impossible, and it is plenty of time.

30 is not a deadline, it is a threshold. You learned from the world, now it is time to start creating your own world.