Psychologist Shigehiro Gishi’s book Life in 3 Dimensions challenges us to rethink what makes a good life. He highlights three crucial dimensions: Happiness (pleasure in the moment), Meaning (a sense of purpose), and Psychological Richness (varied, interesting experiences). Together, they form a powerful framework for understanding well-being.

But the Age Brilliantly mindset pushes this further: after decades of living, we often ask, Was it fulfilling? Did the balance of joy, purpose, and experiences create a life we’re proud of? Fulfillment isn’t about one dimension—it’s about how they come together to create a lasting sense of satisfaction across a 100-year life.

This lens opens the door to fascinating questions about how we live — and how we might live better. One of the most provocative: Do we pursue depth or breadth?

Depth vs. Breadth: Mastery or Variety?

Many of us grew up hearing that success requires focus: 10,000 hours of practice, total commitment, Tiger Woods-level specialization. And indeed, depth — relentless dedication to one craft — often leads to excellence, recognition, and mastery.

But what about breadth? Michael Jordan famously switched sports. Beethoven explored composition beyond what anyone imagined possible. Many thriving modern careers involve reinvention — pivoting industries, learning new skills, exploring passions beyond a single specialty. Breadth fosters adaptability, creativity, and resilience — qualities essential for a 100-year life.

Research highlighted in Gishi’s work suggests that variety—not just depth—can lead to greater long-term satisfaction. Diverse experiences enrich psychological richness and prevent burnout. Breadth can also enhance depth: hobbies, side pursuits, and social variety fuel innovation and joy in our main endeavors.

Routine vs. Spontaneity: Finding Balance

Related to depth and breadth is another dimension: routine versus spontaneity. Routines provide structure and mastery but can harden into monotony over decades. Spontaneity — trying new foods, traveling spontaneously, playing with ideas — sparks curiosity and psychological richness.

A fulfilling life isn’t choosing one over the other but balancing both: maintaining habits that support health and purpose while leaving room for serendipity and playfulness.

The Challenge of Social Vibrancy

Fulfillment also hinges on relationships. As we age, friendships can fade due to distance, health, or changing life stages. Social networks don’t replenish themselves automatically — especially outside school or early career environments. The key is intentional living: seeking out new connections, nurturing intergenerational friendships, and engaging in communities where values align (clubs, volunteering, learning groups). Research consistently links vibrant social lives to longevity and happiness — yet this requires effort as we get older.

Why Playfulness Matters

As life responsibilities grow, play often fades. We become serious, schedule-bound, focused on efficiency. But play — curiosity, humor, delight — is essential for psychological richness and, ultimately, fulfillment. Adding playful elements to routines (turning workouts into dance sessions, cooking as an experiment) can reignite joy and prevent life from feeling like a checklist.

Bringing It All Together: The Fulfillment Question

A fulfilling life blends happiness, meaning, psychological richness — and then reflects on them: Is this the life I want to keep building? This fourth dimension, Fulfillment, evolves as we do. It’s not about perfect balance but about regularly reevaluating what matters, especially across decades.

The Age Brilliantly mindset reframes life as a portfolio, not a single path: one where depth and breadth, routine and spontaneity, seriousness and playfulness shift over time. By intentionally adjusting these dimensions, we can design a 100-year life that is not just long, but deeply satisfying.

Which dimension do you focus on most — happiness, meaning, richness, or fulfillment? Are you living for depth or breadth right now, and would shifting bring you more satisfaction? Share your reflections in the Age Brilliantly Forum and explore how others are designing their own fulfilling lives.

This article is part of the “Life in Four Dimensions” series, exploring how happiness, meaning, psychological richness, and fulfillment shape a 100-year life. Read the next piece in the series: Routine vs. Spontaneity