When researchers compared students’ grades with nearly three dozen personality traits, self-control turned out to be the only trait that predicted a college student’s grade-point average better than chance. Self-control also proved to be a better predictor of college grades than the student’s IQ or SAT score. Although raw intelligence was obviously an advantage, the study showed that self-control was more important because it helped the students show up more reliably for classes, start their homework earlier, and spend more time working and less time watching television.
So if you’d like some advance warning of trouble, look not for a single symptom but rather for a change in the overall intensity of your feelings. If you find yourself especially bothered by frustrating events, or saddened by unpleasant thoughts, or even happier about some good news—then maybe it’s because your brain’s circuits aren’t controlling emotions as well as usual. Now, intense feelings can be quite pleasurable and are an essential part of life, and we’re not suggesting that you strive for emotional monotony (unless you aspire to Mr. Spock’s Vulcan calm). But be aware of...
Focus on one project at a time. If you set more than one self-improvement goal, you may succeed for a while by drawing on reserves to power through, but that just leaves you more depleted and more prone to serious mistakes later. When people have to make a big change in their lives, their efforts are undermined if they are trying to make other changes as well. People who are trying to quit smoking, for example, will have their best shot at succeeding if they aren’t changing other behaviors at the same time. Those who try to quit smoking while also restricting their eating or cutting back on...
Whatever the legal or moral merits of that argument, there certainly was scientific data showing a correlation between blood sugar and criminal behavior. One study found below-average glucose levels in 90 percent of the juvenile delinquents recently taken into custody. Other studies reported that people with hypoglycemia were more likely to be convicted of a wide variety of offenses: traffic violations, public profanity, shoplifting, destruction of property, exhibitionism, public masturbation, embezzlement, arson, spouse abuse, and child abuse.