To get started you need to believe that you are able to do important things. One way to approach this is to repeatedly ask The Hamming question.
Among the important properties to have is the belief you can do important things. If you do not work on important problems how can you expect to do important work? Yet, direct observation, and direct questioning of people, shows most scientists spend most of their time working on things they believe are not important nor are they likely to lead to important things.
If you do not work on important problems then it is obvious you have little chance of doing important things.