Whether it's getting a new job, saving towards a dream purchase or making healthier choices, now is the perfect time to come up with some New Year's Resolutions - that you'll probably never stick to.

91 per cent of people fail to keep their new year's resolutions, with 23 per cent giving up in the first week of January.

But why are we all so unmotivated?

Well, researchers suggests there could be more to the psychology behind it than first thought.

In fact, scientists from the University of Michigan say people's inability to distinguish willpower from self-control could be the cause, because of shifts in the meaning of the words over time.

Most people use both willpower and self-control as words to refer to resisting temptation in the moment, when actually, it's about a long-term strategy.

Self-control is really about changing your behaviour to achieve goals, improve positive outcomes, and avoid consequences. Meanwhile, willpower is about those small bursts of temptation being overcome to get to where you need to be.

"If a social scientist told his patients to exercise self-control to avoid sweets, they would think he meant resisting the immediate craving to eat a freshly baked cookie. They would not think he meant taking the long route home to avoid driving past the bakery," says Chandra Sripada, a psychiatric neuroscientist and philosopher at the University of Michigan.

“You have to communicate with people using a familiar vocabulary."

This shift in language is thought to have taken place over thousands of years, dating back to Greek mythology.

Philosopher Plato even went in the total opposite direction with the meaning of the self-control we know now, and asserted that self-control compensated for a lack of strategic planning.

This confusion can be particularly harmful when it comes to setting New Year's Resolutions. Scientists say experts and the media need to reframe how they speak about achieving your goals at this time of year, in order to help people stick to them.

Sripada adds: “Do you want to keep your New Year’s Resolutions? Then don’t rely on self-control. That is a sucker’s game.”