Broken down:
If you aren't going to do something awesome (like travel a lot), [then] why not work hard [instead]?
If you're going to do something awesome, why not work hard [to achieve great things]?
or
If you're not going to something awesome, why work hard [because what's the point if it's not awesome]?
If you're going to do something awesome, why not work hard [to achieve great things]?
or
If you're not going to something awesome, why work hard [because what's the point if it's not awesome]?