Go after the hardest thing
JFK got it right - don't do things because they are easy, but because they are hard. We only have one shot at life, so why waste it taking the easy road? If our ancestors took the easy path, who knows where we would be right now. All I know is we wouldn't have cars, phones, or the other magnitude of inventions that we all take for granted.
Something I heard recently that I'm guilty of forgetting is that everything in the world around us was built by people no smarter than us. Every building, every technology, everything we see, it wasn't there before us humans evolved on this planet. They don't just magically spawn in. Somebody had to pour their blood, sweat, and tears into making the world a better place for the people of tomorrow.
I truly believe that that's a big part of why a small handful of people build the courage to attack the most difficult problems: If not us, then who? If not now, then when? Read that again.
As humanity, we have a duty to face the toughest challenges head on for our fellow, future humans. To leave our planet better than how we found it. That's what it's all about, and it's so god damn inspiring.
Just imagine the amount of people who came before you to give you the ability to be here, breathing, living today. The struggles, the hopes, the dreams that have lived to allow you to have the chance to leave your mark.
We owe it to them to go after that thing that scares us. Just do it, try to make a dent. You will often be surprised by how far you can go. That being said, chase the hardest, most impactful problem you can find. Do it for you, do it for your fellow humans - past, present, and future.