I made it to managing director after 17 years in banking, and then I quit. I didn't want to work myself into the ground well into my 60s.

• Eric Sim spent more than 20 years in banking, working in Singapore, London, Shanghai, and Hong Kong.
• The engineering major says he knew very little about banking when he graduated.
• Sim left banking in 2017 and is now a published author, professional speaker, and career coach.

This as-told-to essay is based on a conversation with Eric Sim, 54, a former banker who became a professional speaker and executive coach. The following has been edited for length and clarity. Business Insider has verified his education and employment history.

When I picked banking as a career, I had very little idea of what the job would actually involve. I'd never even heard of the big names like Goldman Sachs and Morgan Stanley — but banking felt novel and challenging to me.

My first job out of school was at DBS Bank, where I did corporate foreign-exchange sales. I was an engineering graduate and not as savvy as my colleagues, who majored in business administration.

After two years, I decided to leave DBS and get my master's in finance at Lancaster University. I wasn't able to secure a job in London, though. I ended up returning to Singapore in the thick of the 1997 Asian Financial Crisis.

As jobs were scarce, I decided to take work in risk management instead. That was when I joined Standard Chartered.

I was fortunate to have a good boss. He really believed in me and sent me on secondments to London and Hong Kong. That kickstarted my international career.

I later moved on to Citibank in 2001, where I worked on global markets. In 2005, I saw that China was liberalizing its financial sector, so I asked my boss to post me to China, and I spent two years there.

Working in China was eye-opening. Compared to a small country like Singapore, there were lots more industries, such as mining and shipping, to cover.

I then relocated to Hong Kong and switched my focus to investment banking and Asia-centric transactions. That paved the way for me to join UBS as a managing director.

I can play the game, but I don't enjoy the game

To be honest, I've always thought of leaving banking. Back in 2005, I thought of returning to college to study architecture. I applied for a spot and got accepted into the program after passing a test.

But I decided against it. If I went back to school, I would have to study for five years and accrue two years of practical experience before I could qualify as an architect.

That was a huge opportunity cost for me, as I would have made well over a million dollars if I had stayed with banking during the same period. I was in my mid-30s then, and I still had to pay my mortgage. It didn't make financial sense to leave banking then.

That said, I also recognized that while I could play the game, I didn't enjoy it. For most people who go into banking, the norm is to work as much as you can and retire when you're 60.

However, that leaves you with very limited choices in life. Your health may deteriorate, and you won't be able to travel as much.

So after spending over 20 years in banking, I left UBS in 2017.

At that point, my health was still good, and I had sufficient savings. That meant that I could pursue the things I liked and start a new career in professional speaking and executive coaching.

In this phase of my life, I'm now focusing on satisfaction, meaning, and fulfillment. Through my work as a speaker and lecturer, I have been able to share my know-how in banking and career planning with more people.

It's a lot harder to make it in banking these days

Banking is really just a sales job. It is about knowing what your customer wants and then building a relationship. You want to be the first person the client calls when they have a problem.

But succeeding in banking is a lot harder these days. In the past, there was less competition and less regulation within the sector. It was easier for the banks to make money.

Things are different now. After the 2008 Global Financial Crisis, a lot more people now know how much money bankers can make. There is a lot more competition for banking jobs.

But even if I could turn the clock back, I would still pick banking as a career. Banking is an excellent industry for self-development.

My advice to young professionals is to seek out job opportunities that allow them to learn. That has been my career principle, and it has served me well.