> Deciding what to work on might be the most important question in life.

The flip side of this, is if you have the ability, you can just pick the hardest problem in your field, go solve it... rinse and repeat.

Everyone can find out what the hardest problems in their field are, it's not a secret, just a question of if you have the ability/gumption/willingness to go spend years of your life attacking a problem like that