Whether you're saving money or spending it, star of CNBC's "The Profit" and serial entrepreneur Marcus Lemonis has the same advice for you: Know your numbers.

"You have to understand what your needs are and what you can actually afford," Lemonis told CNBC.

The self-made millionaire sets rules for himself. He doesn't like racking up debt, and he ensures a portion of his paychecks goes to savings.