We all have habits we like to break, whether it's biting your fingernails, smoking or eating late at night.

But why are these habits so hard to break?

Perhaps you think your day is made up of deliberate conscious decisions,

but in reality, the University of Duke study found that 45% of your everyday behaviors are actions that you repeat everyday and tend to do in the same location.

These are your habits.

Habits are attributed to one of the most primitive structures in your brain, the basal ganglia, the same region that helps control processes such as breathing and swallowing.

In an MIT experiment, a mouse sits behind a gate of a T-shaped maze where to the left is a piece of chocolate.

When the door clicks, the mouse explores the maze, sniffing and scratching up the walls.

First it explores to the right and then to the left, eventually finding the chocolate.

A scan of their basal ganglia shows it's working furiously throughout the whole process.

However, after a week of training, the mouse runs immediately towards the chocolate once the gate clicks.

At this point, there is very little brain activity once the gate clicks and the brain doesn't fire back up again until it reaches the chocolate.

Our brain seek to minimize effort and space, and this kind of automatic brain behavior is referred to as "chunking".

Chunking aids in creating a new habit pattern in cells of the brain.

It's like a task you do everyday that you no longer really have to think about.

Brushing your teeth or backing out of your driveway, skills that were once difficult to master but now become automatic.

This process is a 3-step loop.

Step 1 is the cue, which, for the mouse, is click of the gate.

Step 2 is routine, run through the base

and step 3 is the reward, in this case, chocolate.

The cue and reward eventually intertwine, creating anticipation and cravings, another central part of habits.

Because we go into automatic mode during routines, our brain stops fully participating in decision-making.

Our habits will automatically unfold every time there is a cue.

These habits can be so entrenched that the rewards doesn't even have to be good.

A study of habitual popcorn eaters at the movies found that they were minimally impacted by hunger or how much they liked the food and they ate the same amount of popcorn, regardless of whether it was stale or fresh.

Our habits often overrule what we know is good for us.

For example, a study of America's "TAKE 5" campaign to encourage citizens to eat 5 fruits and vegetables a day, found the program was effective in educating the public,

but an assessment found that it did not change American intake, where only 11% met the goal.

It changed people's intentions but not their habits.

So, what are you to do?

Charles Duhigg, author of "THE POWER OF HABIT," gives an example of buying a cookie everyday around 3:15pm at work.

The cue is 3 o'clock but the reward is a bit more complicated, as the cookie can be a bundle of many rewards.

It could be a relief from hunger or an energy boost to satiate your craving for something sweet or it could be a nice break from work or even an opportunity to talk to people.

Duhigg wanted to break his cookie habit, and after some trial and error, discovered that what he really craved was socialization that came from buying the cookie.

So, around 3, he would get up and find someone to gossip with for 10 minutes instead.

By using the same cue and the same reward of socialization, he was able to break the cookie habit.

But what about the habits that you don't always notice, like biting your nails.

Psychologists suggest that first you think about "when" you bite your nails.

Are you nervous or bored?

In the case of boredom, nail-biting offers a "physical stimulation".

So, next, you need to mark down every time in your day you feel bored and have the compulsion to bite your nails.

Maybe that's 5 times a day, maybe its 28.

But then you want to implement a "competing response".

Whenever you feel the desire to bite, you immediately put your hands in your pockets.

Next, find a substitute that provides a quick physical stimulation, like rubbing your arm or tapping your knuckles on the desk.

This allows for one habit to be replaced by another with a similar reward but also uses the same cue.

So, when you are ready to take on a bad habit, just remember, figure out what your body is actually craving, use the same cue and the reward that serves the correct purpose and be patient to help build that new habit.