Work ethic usually means work harder OR smarter, but it's often hard to work smart without initially working hard.
Unless you're an incredible genius, building up a solid technical/reputational foundation for your career takes at least a few years of really hard work at the start of your career. Particularly when most of the lucrative careers are so competitive now.
In my profession, the earnings are pyramid shaped and if you want to maximise your earnings it will take you either 3-5 years of hellish work at the beginning of your career, or 10 years of grinding at the tail end. I know which I'd prefer.
There's no magic antidote whereby I could achieve the level of earnings I want without putting in some serious hours at the start. The same would apply to most serious professionals, musicians, athletes, etc. You have to practise hard at the start, and that means when you're in your 20s/30s.