What does "more will power trumps less" mean?

That is meaningless in practical matters. When people seem to lack motivation it is somewhat more likely that they don't know how to do what is asked of them, or the reward for the effort does not seem adequate. I have known some very successful people and almost every one of them did not actually know how they did it. They only knew it took a lot of effort. So if someone else could not duplicate their results, they assumed it must be because he was lazy.

George Santayana ~ 'Fanaticism consists of redoubling your efforts when you have forgotten your aim.'

'Motivation makes no difference if your plan doesn't work.'

'The road to hell is paved with good intentions.'

There are many such slogans.