The Maturity Principle of Grit
Understand that grit develops naturally with age through life experience and adaptation
Duckworth presents data showing that grit scores increase steadily with age: adults in their late sixties score significantly higher than those in their twenties. While this could reflect generational differences (the Greatest Generation being culturally grittier than millennials), Duckworth argues that the more compelling explanation is the maturity principle — the well-documented finding that personality develops throughout the lifespan as people learn from experience and adapt to demanding circumstances.
The maturity principle operates through two mechanisms. First, we learn things we didn't know before: that being a 'promising beginner' is fun but being an expert is more gratifying, that sustained commitment outperforms serial enthusiasm, and that effort often looks like innate talent from the outside. Second, our circumstances change and we adapt: getting a first job, becoming a parent, and facing real consequences for failure all reshape our behavior and eventually our identity.
Grit is not fixed at birth or crystallized in childhood. The heritability of grit is estimated at 20-37 percent, comparable to other personality traits, meaning a substantial portion is shaped by experience. Like all aspects of personality, grit is plastic — it changes in response to what life demands of us. This means that your current grit score is a snapshot, not a sentence, and that deliberate cultivation can accelerate what maturity would eventually produce naturally.
- Grit scores increase with age across large population samples
- Personality develops throughout the lifespan — there is no age at which it stops evolving
- We change through learning (insight) and adaptation (responding to demanding circumstances)
- Necessity is the mother of adaptation — new roles and responsibilities reshape us
- Grit is influenced by both genetics (20-37% heritability) and experience
- Your current grit score is a snapshot, not a permanent trait
- Deliberate cultivation can accelerate what maturity would eventually produce
- Accept your current grit level as a starting pointTake the Grit Scale and note your score without judgment. Recognize that wherever you are today is partly a function of your age and life experience. The data shows that most people naturally develop more grit over time.
- Seek experiences that demand adaptationPlace yourself in situations that require you to be grittier than you currently are. Just as Duckworth's daughter Lucy was potty-trained in a single day when placed in a classroom where it was expected, people rise to the demands of their environment.
- Learn from the insights of experienceReflect on what your successes and failures have taught you about the value of sustained commitment. Many people learn through trial and error that repeatedly swapping career ambitions is unfulfilling. Use these insights to inform future decisions rather than repeating the cycle.
- Accelerate maturation through deliberate grit developmentDon't wait passively for time to do its work. Actively cultivate interest, practice, purpose, and hope. Join gritty cultures. Follow the Hard Thing Rule. The maturity principle tells you change is inevitable; deliberate effort determines how fast and how far you develop.
Lakeside School headmaster Bernie Noe's daughter was chronically late to school throughout her teenage years despite repeated conversations. One summer she got a job at American Eagle, where the manager told her on day one: 'The first time you're late, you're fired.' No second chances. The result was immediate and dramatic: she started setting two alarms and was never late.
Duckworth discovered the age-grit relationship in large-scale surveys of American adults and connected it to the personality psychology literature on the maturity principle. Her own life exemplified the pattern: in her twenties, she cycled through a nonprofit, neuroscience research, management consulting, and teaching before discovering psychology as her calling. She contrasted her experience with a Wharton entrepreneur who expected to move on to something new within a few years, and with her father, who gave his entire career to DuPont.