12/01/2015 11:02 GMT | Updated 14/03/2015 05:59 GMT

New Year's Resolutions: Don't Feel a Failure

If I were a betting woman I'd happily run a book on people not keeping to their New Year resolutions. My friend Sue fell off the wagon before the tinsel had even been taken down. After a resolution for an alcohol-free January she was lured over to the dark side by a family crisis and a leftover bottle of bubbly. Another gym-bunny buddy noticed the gym was heaving in the first week of January, but so quiet in the second week he was convinced an emergency had caused the place to be evacuated.

Psychologists know the best predictor of future human behaviour is past behaviour. And willpower is so weak it barely exists. So resolution-failure is a pretty safe bet.

Humans have been making resolutions since Roman times and more than half are health-related so we might wonder why we are doomed to fail by mid-January, when we had the very best of intentions just two weeks before?

Here are some of the reasons that science has uncovered:

1. Lofty goals. When it comes to resolutions many people aim far too high. Like saying, "I'll lose a stone in a month". When the scales dip by a mere pound mid-January, hopes of success are soon dashed. That's when that "what the hell" moment kicks in and the dieter finds him or herself sitting in on the sofa with a pile of cakes. This is known as behavioural rebound,and may explain why people buy more food after the new year.

On the other hand a goal that is more realistic specifies a positive do-able behaviour. Like 'I'll swap one of my unhealthy snacks every day for a piece of fruit'.

DO: Set yourself realistic goals so change can happen in small, do-able steps.

2. Failing to reshape the environment. Studies show that the triggers for our past, unwanted behaviours surround us every day. And our conditioned brain reacts automatically to those triggers, making change tough and willpower powerless. That's why trying to eat healthily while there is still Christmas cake in the tin is hard. Better to feed it to the birds. Then hide the junk food and put the fruit bowl in the space usually occupied by the biscuit tin.

DO: Rearrange your personal space to remove temptation and facilitate the changes you want.

3. Sticking to the same routines and habits. The brain is the ultimate habit machine. Your life has unknowingly been sent down a set of rails, and your cunning brain switched to autopilot. Making changes means seizing back control. To do this you have to shake up those old habits and routines, take new routes, spend time with different people, go to new places. Simply be prepared to flex and do something different every day. It may be instinctive to buy your usual cappuccino if you pass the same coffee bar every day. But go in a different direction and you just might end up in a juice bar instead.

DO: Shake up old habits and routines and do something different every day.

If you find it tough to break old habits and are fed up with failed resolutions, try an app or online programme, such as Do Something Different, for support.