Think back to when you were 10 years old – what were you like and what did you value? For me, my primary memory is of playing tennis. My life was consumed by the sport. During the school holidays, I played all day, every day at my local club. And I’d just started to play statewide tournaments. There wasn’t a lot else that got my attention, including school, back then.

Fast forward to 20 years of age, I was at university and loved learning and education. Earlier, I had a sliding doors moment, deciding that I wanted to pursue education instead of becoming a professional tennis player. I still coached some tennis to earn some money for socializing while attending university but had largely given up playing. My 10-year-old self wouldn’t have fathomed what I’d become a decade later.

By 30, I lived in Indonesia as a research analyst at a stockbroker. I’d moved to Asia when I was 29, and had short work rotations in Hong Kong, Shanghai, and Singapore. If you’d told me when I was 20 what I’d be doing when I was 30, I’d have thought you crazy. Going from studying history and politics at university, to five years as a journalist at the ABC, and then crossing over into finance – nuts. And living in Indonesia to boot...

At 40 years of age, I lived in Sydney with a wife and child. I had started my own business, though was probably a bit lost after becoming disillusioned with the corporate world. While at 30 I was focused on succeeding in a finance career, making money, and travelling a lot, that had all turned on its head ten years later.

Turning to today and I am 48, with two kids, and back in the corporate world. I enjoy my work which combines writing and investing. I enjoy my life outside of work which primarily involves kids’ activities. Three months after I turned 40, my family bought a motel, which we still own. For health reasons, I turned vegan about seven years ago. Also, for health reasons, I took up meditation and it’s changing my life. My 40-year-old self would be scratching his head if you’d told him what I’d be like just eight years later.

Why do we change so much?

How do we become different people at different stages of life? Obviously, the ageing process has a lot to do with it. Our minds and bodies change. For instance, our ability to think abstractly and deal with complex information – called fluid intelligence – peaks at 20 years of age and declines each year after that. Yet, our decision making improves through to our 50s because of experience, and the wisdom that comes from that experience.

Of course, our bodies age too. We can’t physically do the things we did in our teens when reach the 40s, 50s, and 60s.

Our environment also shapes us - where we live and work, and who we socialize with. Often, we don’t realise how much our environment influences who we are.

Genetics also play a part. Interestingly, different genes can express themselves, or becomedominant, at different points in our lives.

Neuroscientists are discovering new things about why we age. They’ve found that our brains change not just due to mechanical processes such as fluid intelligence, but also because what we focus on each day, and each moment, rewires the brain over time. For example, if you decide to learn a language, your brain will physically change over time and influence thinking and behaviour thereafter. Or, if you decide to re-learn an instrument that you played when you were younger, that will alter your brain circuitry. Put simply, what you focus on changes your brain and your future self.

Implications for life and money

If our priorities, values, and goals constantly shift as we age, it has significant implications for how we should live and think about money.

It’s drummed into us from a young age that we should set goals and make plans to achieve them. Later, we’re taught that financial planning and goal setting are vital to secure our futures. Yet, if our financial goals and plans change as we get older, not once but numerous times, then the pursuit of both is likely to disappoint.

That’s not to say that financial planning and goal setting are a waste of time. It’s that both should be lightly held, with an acknowledgement that adjustments will be needed along the way.

An alternative path is along the lines of what the latest neuroscience is suggesting above. If what we pay attention to now shapes our brains and future selves, then it may be best to focus on the thinking and habits that can build a better person and financial future. Put another way, how we spend today ultimately determines both our past and our future.