How do you want to change the world as a person?

@yanbe posted a question "How do you want to change the world as an web engineer?" to Hachiroku Skype chat. This is frequently asked question, he says, in Silicon Valley.
I think this question is appliable to how you live in your life. The question can be extended, for example:

"How do you want to change the world?"

If you can answer this abstract question, the answer will be applicable to other questions: "as an web engineer", "as a banker", and "as a working person".