The biggest mistake people make when asking for a raise

Having a great career isn't just about money. But most people make the mistake of thinking it is.

Whether you're negotiating a new job offer or asking for a raise, a simple shift in thinking could increase your gains, negotiation speaker and strategist Keld Jensen told CNBC.

Jensen is the author of more than 20 books on the subject, including "The Trust Factor" and "Negotiating Partnerships," and an adjunct professor at Arizona State University's Thunderbird School of Global Management.

"Most people are negotiating on too few variables," Jensen said.

For example if you were negotiating a raise or a job offer, consider asking for other variables in addition to more money, such as:

• The ability to work remotely once a week

• More personal days or vacation time

• Flexible hours (that could allow you to take your kids to school or squeeze in check ups)

Suggesting these variables while also asking for more money could actually help your case, Jensen said.

Employers sometimes view a raise as a zero-sum game, he explained, where the employer thinks about it as a "loss" to the company.

"Instead of getting a huge increase in your salary, perhaps working from home could generate a greater value for you," he said. Meanwhile, "the cost to the employer might be very low."

That rationale is what Jensen calls "negoeconomics," or the economics of negotiation.

"In simple terms, it means that 2+2 equals more than 4 because you will find something that has a high value to you but a lower cost to your counterpart," he said.

"Even before you start a negotiation, you should be creative — sitting down and just thinking on the full potential of variables that you could negotiate," Jensen said.

Video by Mary Stevens.

Correction: This article has been updated to correct that the Thunderbird School of Global Management is part of Arizona State University.