It's a common lament that our lack of will power often leaves us unable to resist life's temptations - whether it's retail therapy, chocolate or wine.
Even if we try hard to strengthen our elusive mental resolve to say "no" and dutifully make resolutions annually, we frequently fail and become further discouraged by our "weakness".
But it may not be all our fault, says Roy F Baumeister, co-author of Willpower: Why Self-Control Is The Secret To Success, who reveals how to boost will power.
"People frequently feel overwhelmed these days because there are more temptations than ever to seduce us and distract us from our goals," he points out.
"You can put off any job by checking email or Facebook, surfing gossip sites or playing a video game. You can do enough damage in a 10-minute shopping spree to wreck your budget for the rest of the year."
He and fellow author John Tierney, who've spent years researching will power, found that people spend at least a fifth of their waking hours (three to four hours daily) resisting desires, and this doesn't include the time spent using will power to make decisions.
The most commonly resisted desire, in one study they examined, was the urge to eat, followed by the urge to sleep, break off from work, succumb to sexual urges, and finally surf the web or watch television.
Generally, people were relatively effective at avoiding naps, sex and the urge to spend money, only mediocre at passing up food and soft drinks, but failed nearly half the time on resisting the lure of TV and the web.
Yet improving will power is the best route to a better life, benefiting every area from personal life to career, according to Baumeister, and he believes we can strengthen our mental resolve by exercising it, just as we might exercise our muscles.
"However you define success, it can't be achieved without first mastering self-control and exercising will power," he says.
"Ultimately, it takes practice and self-awareness but the rewards are huge. Improved self-control will let you relax because it removes stress, enabling you to conserve will power for the important challenges.
"Toning up your will power will help you lead a more productive and fulfilling life and one which is easier and happier."
Follow the simple 10-step plan to gain will power.
Diet and will power
Various research, says Baumeister, has highlighted the fact that low glucose levels in the body can leave people less able to control their will, to indulge in risky behaviour or be prone to temptation.
Mental energy is fuelled by the glucose in the body's blood stream, so to help maintain steady self-control he suggests eating foods with a low glycaemic index.
Those are foods such as vegetables, nuts including peanuts and cashews, raw fruits such as apples, blueberries and pears, cheese, fish, meat, and olive oil.
Having those present in a diet will help give a sustained dose of glucose to the body, rather than a "quick hit" derived from high glycaemic foods such as white bread, potatoes, white rice and fast food. The latter leaves you vulnerable to spikes in energy and therefore vulnerable to lack of control and cravings.
Hit the snooze button
Set aside enough time to sleep, Baumeister advises.
"Lack of sleep has assorted bad effects on mind and body. Hidden among these is the weakening of self-control and related processes like decision making."
"Adults routinely short-change themselves on sleep, and the result is less self-control. By resting we reduce the body's demands for glucose and we also improve its overall ability to make use of the glucose in the bloodstream."
He says a recent study found that workers who didn't get enough sleep were more prone than others to engage in unethical conduct on the job, and more likely to falsely take credit for work actually done by others.
Will power workout
Try overriding a small but habitual bad habit, perhaps slouching when you sit at your desk, or avoiding bad speech habits such as peppering your conversation with "you know" or "like".
Set yourself a time-limit of a month to eradicate the habit, and practise it when your will-power is at its strongest, early in the day.
Research, Baumeister cites, found that engaging in small will power boosting exercises, and achieving success, acts as a warm-up for tackling a bigger challenge, and makes the will power more resilient.
Know your limits
Recognise that will power is finite and can become tired by overuse. Each day may start with your stock of will power fresh and renewed, but throughout the day events will chip away at it.
"You pull yourself out of bed even though your body wants more sleep. You put up with traffic frustrations. You hold your tongue when your boss or partner angers you," says Baumeister. "You try to maintain an interested, alert expression on your face while a colleague drones on during a boring meeting. But remember that what matters is the exertion, not the outcome."
Acknowledging the times you've managed to use your willpower will boost your self-esteem.
Rest and refresh your will
The old advice that things will seem better in the morning has nothing to do with daylight.
"Beware of making binding decisions when your energy is down, late at night or when you're exhausted, because you'll tend to favour options with short-term gains and delayed costs."
"You can't control or predict the stresses that come into your life but you can use calm periods to plan a strategy for dealing with them when they do. Then you're more likely to have the reserves of will power to cope with real challenges," Baumeister says.
Will power plan
Put your life in perspective by setting aside a day for reflection each year, like your birthday.
"Ask yourself whether you are where you want to be, what could be better and what you could do about it. Aim for a broad five-year plan along with more specific, manageable monthly goals," says Baumeister. "A plan leads to a clearer mind and allowing you to see where the challenges lie."
Limit your target
Don't make a list of goals - nobody has enough will power to cover a huge list of challenges from dieting to giving up smoking.
"When people have to make a big change in their lives, their efforts are undermined if they are seeking to simultaneously make other changes as well," says Baumeister.
"Those goals will simply compete with one another and each time you try to follow one, you reduce your capacity for all the others."
"Instead make one resolution, stick to it, and by succeeding you'll boost your belief in your will power."
He cites research which showed that those who tried to control their drinking tended to fail on days when they had other demands on their self-control, compared with those days when they devoted all their efforts to limit their drinking.
Whenever you set a goal, beware the tendency to be over-optimistic.
"When was the last time you heard of a road or building being completed six months early? Late and over-budget is the norm," he says.
"So always leave some flexibility and anticipate set-backs when you plan otherwise you'll get discouraged easily, which will further confirm your belief that you have weak will power when actually you're probably just guilty of setting yourself an unrealistic target."
Will power budget
"If there are extra challenges ahead in your life, like doing your income tax or travelling or facing a tricky work period, figure out where you'll get the extra will power to cope," says Baumeister.
"That could be by cutting back on other demands on your will power in less crucial areas of your life, whether it's resolving to tidy the house or stick to an exercise routine."
Delay don't deny
People who procrastinate continually can be criticised but this can be a positive trait.
"People tempted by chocolate can avoid it by telling themselves they'd have it some other time - a postponement strategy which works better than trying to deny themselves altogether," he says.
"It can also work for other temptations from over-eating to watching television. But make sure that when you do succeed you reward your efforts. If you give up smoking, use the money you have saved to buy a treat for yourself.
"And, remember that exercising will power brings joy as inner discipline leads to outer kindness. Those with stronger will power are more altruistic and likely to help others, donate to charity and look for ways to help their family as well as strangers."
Willpower: Why Self-Control Is The Secret To Success, by Roy F. Baumeister and John Tierney, is published by Penguin. AAP