in earnest

[GUEST2008]

Hi

Concentration means success, because you are better able to govern yourself and centralize your mind; you become more in earnest in what you do and this almost invariably improves your chances for success.

Does it mean that one becomes more serious in what one does? For example I do something more seriously?

[emsr2d2]

Hi

Concentration means success, because you are better able to govern yourself and centralize your mind; you become more in earnest in what you do and this almost invariably improves your chances for success.

Does it mean that one becomes more serious in what one does? For example I do something more seriously?

In my opinion, using "in earnest" here is incorrect. If used at all here, it should simply be "you become more earnest in what you do". Your interpretation is correct, though.

He is very earnest.
The presidential campaign began in earnest yesterday.