We learn from our mistakes

Jumping on the second wave of your career path

How to overcome the decline in performance with age by moving from fluid to crystallised intelligence, finding new opportunities for growth and well-being

by Giulio Xhaet*

2 December 2025

Aggiungi Il Sole 24 Ore
ai preferiti su Google

4' min read

Translated by AI

Versione italiana

4' min read

Translated by AI

Versione italiana

I recently read a book from which I drew valuable insights to set up mentorship paths with some companies. It is calledThe Second Wave, an essay that mixes the author's experiences with a frankness and acumen that is rare.

The author is Arthur C. Brooks who, after many years as a professional musician (French horn player), now teaches "leadership & happiness studies" at the Harvard Kennedy School, with an eclectic approach that combines science, philosophy, religion and business. And he is considered one of the leading contemporary voices on the subject of well-being, personal purpose and human leadership.

In the first pages he states: 'I have uncovered a universal source of angst among people who have been successful in their craft. I have called it the 'curse of the ambitious': the more excellent you have been, the more terrifying the decline will seem'.

When does professional decline begin? Despite the fact that we are much longer-lived than in the past, Brooks explains that "in almost every highly skilled profession the decline is between the late thirties and early fifties." He continues: "I'm sorry, I know it hurts. And it doesn't end there: the more accomplished you are at the peak of your career, the more pronounced the decline appears once it starts'.

Here we need to clarify: what is it that declines? Certainly the ability to perform at one's best, with little effort. Then implementing radical innovation consistently, and very often (but not always) the entrepreneurial spirit linked to a hunger for new challenges and continuous proactivity. In short, the famous Stay Hungry Stay Foolish attitude would tend to fade, if not disappear, as one enters the 'old age'.

Of course, it depends on the profession: statistically, for example, for writers the decline would start on average between the ages of 40 and 55. Finance professionals reach their peak between the ages of 36 and 40. Doctors, after the age of 40, on average experience drastic declines in competence and memory. A fact that as a patient does not hearten me at all. Whereas among the most 'long-lived' professions are historians, who often peak after the age of 60.

If you want to go deeper, look for studies such as Curvilinear Relationships Between Age and Job Performance and Adaptivity/ Proactivity or Universal Productivity Patterns in Research Careers.

Professional peak after 20 years of work

Another research shows the decline from another perspective: if one does not change jobs completely, the peak is reached after about 20 years in that job. Although I repeat, the exact numbers vary greatly depending on profession, context and individual.

But the point is another. Returning to the initial cue: great abilities and successes at an early stage of life are by no means a policy against suffering at a later stage. Quite the contrary. Data show that people of great excellence and reputation in their professional lives tend to be more unhappy than others when they have to quit.

"The inability to store up glory to enjoy it when it is gone is creating a horde of dissatisfaction. Human beings are not made to enjoy a past success".

Moreover, we hardly pity a successful person. The suffering of the ambitious person seems to us an unfounded whimper. Yet it is real.

So, how to protect oneself, what to do?

Fortunately, Brooks noted how at 30, 40, 50, 80... you name the age, when we have peaked in something performance-wise, it's not over. We can decide to jump from the first to the second 'wave'.

Two types of intelligence

To understand the metaphor, we are helped by psychologist Raymond Cattell, who in the 1970s hypothesised that there were two types of intelligence. Or rather, two ways of using the different intelligences within us (such as classic IQ, emotional intelligence and social intelligence). He christened them fluid intelligence and crystallised intelligence.

The first wave creates fluid intelligence: the ability to think flexibly, ride changes, face new problems and challenges. This 'free-range' intelligence grows in the teens and twenties, but already fades by the 30s and 40s.

The subject of the second wave, on the other hand, is crystallised intelligence, i.e. the ability to use the reserves of knowledge accumulated in the past.

This intelligence, if facilitated, tends to increase over the years, after 40, 50, 60, continuing to develop into old age. Returning to Brooks' words: 'When you are young you generate a lot of new facts more easily. When you get older you understand more easily what they mean and how to use them."

On average, you will have less innovative ideas and energy, but you will be better able to synthesise and understand them in depth. Not only that, crystallised intelligence helps us to better interpret our own and others' ideas and actions. We can more easily understand other people, help them, support them, advise them. It is no coincidence that great experiences can result in great mentors.

Teaching is an area typically suited to the second wave: a 1992 study in The Journal of Higher Education showed that the college professors with the best ratings in all departments were, on average, the most senior.

However, the process is not automatic: more years does not always mean more wisdom, quite the contrary. We have the opportunity, hence the potential, to become wiser, but we must seize it and exercise it. And the more complex the world becomes, the more challenging it becomes to harness the benefits of crystallised intelligence.

As is plain for all to see, the planet is currently ruled by old men who mimic the energy and impetuosity of the young, but prove to be lacking in wisdom, and are producing disasters. Are you (or will you be) able to seize this opportunity?

Brooks again: "If you're experiencing a decline in fluid intelligence, and if you're my age you certainly are, you're by no means doomed. It means it's time to jump off the wave of fluid intelligence and get on the wave of crystallised intelligence."

So, whatever your age, good waves of life to you all!

*Partner & Head of Communication, Newton SpA