Hard work is important, I assume he wants to stress the fact that most are lacking this, but I disagree with the "just that" part. It is not just. It is always morality (including reasonable work) + concentration + wisdom. Any one or two singled out of the three, always end up in greater evil to oneself and the entire universe. Not saying don't do anything because you might make a mistake. Do, make a mistake if you have to, but then necesarrily fix the mistake or die before moving on to the next thing. Sounds hard, self destruction, but it isn't. It actually is the only way, while everything else is self destruction.