"Complaining is the absolute worst possible thing you could do for your health or your wealth,

In "Secrets of the Millionaire Mind," author and self-made millionaire T. Harv Eker identifies a seemingly harmless daily habit average people engage in that the rich refuse to: complaining.

"Complaining is the absolute worst possible thing you could do for your health or your wealth," Eker writes.

When you complain, you're focusing on what is wrong with your life — and what you focus on tends to expand, Eker explains.

"Like attracts like," the self-made millionaire writes. "When you are complaining, you are actually attracting 'crap' into your life."

This leaves very little room for growth, particularly financial growth.