In psychology, many of the barriers to clear thinking are self-inflicted. Intelligence is not only about test scores but also about how effectively we can apply our mental abilities in real life—what Robert Sternberg once called “practical intelligence.”

Unfortunately, small daily choices can blunt this potential. Recognizing these mistakes is the first step toward avoiding them. Here are five common ways we unintentionally undermine our own brainpower:

1. Believing intelligence is fixed
   Seeing the mind as unchangeable limits growth. Research with students has shown that those who adopt a “growth mindset” improve academically, while those who believe their ability is set in stone stagnate. Our self-talk shapes our capacity.
   
2. Sacrificing sleep
   Sleep is not wasted time; it is when the brain consolidates memory, repairs itself, and maintains focus. Even mild sleep loss weakens attention, mood, and decision-making. Chronic deprivation leaves the mind sluggish and error-prone.
   
3. Relying on alcohol
   While a drink may feel harmless, frequent or heavy use is tied to long-term brain damage, vascular problems, and even Alzheimer-related changes. Protecting cognitive health means reducing or eliminating regular alcohol intake.
   
4. Lack of structure
   Brains perform best with goals, routines, and deadlines. Without structure, procrastination grows and executive functions decline. Creativity thrives not in chaos but within a framework that provides continuity and momentum.
   
5. Toxic mental environments
   Just as diets shape the body, the “mental diet” of gossip, negativity, and distraction erodes thinking. Emotions and moods spread across social groups, meaning the people and media we expose ourselves to can raise or lower our baseline well-being.
   

The Common Thread
All of these pitfalls take root when self-awareness is missing. By noticing them—then choosing better sleep, healthier company, disciplined routines, and a growth-oriented mindset—we give our brains the chance to perform at their highest level.