I did a maths degree after school, then headed to the City. I worked in insurance for three years, then went into computing and programming. My first senior job was with the Canadian Imperial Bank of Commerce (CIBC).
It was good working in a finance company because that's where the money was. I was part of the technology team, writing programs and making sure everything ran smoothly.
I worked my way up and in 2006, I accepted a two-year contract in Toronto, Canada.
The original plan was that I would then come back and head a team at the London office.
But the credit crunch hit and the company had to downsize and restructure. The London office was cut from 500 to 200 people. Suddenly I didn't have a job to go back to.
I asked myself: "So what do you want to do next?" I thought about various jobs in technology, but the spark wasn't there. I had done programming, operations and the senior management thing before. The jobs that were available would mean doing the same thing all over again.
I had thought about teaching in the past, but hadn't been able to afford it.
My wife and I made the decision that she would stay at home and bring up our family.
We had four kids and we liked nice holidays. To maintain that sort of lifestyle, I needed a high-paying job.
Even before I moved to Canada I thought about teaching again. I didn't have too big a mortgage at that point, but there still wasn't enough money for me to take a year off to retrain.
I was trapped in a cycle of having to earn money to maintain a standard of living. When I was made redundant, my two eldest boys were at university and the younger two were 16 and 14.
The children were less dependant on us, my wife was freer to work, and with the benefit of a redundancy package I finally took the leap into teaching.
I started my GTP (Graduate Teacher Programme) as soon as I could and finished my training at Christmas. I'm now working at St Edward's School in Romford, Essex, teaching maths to 11 to 18-year-olds.
It has changed everything. Even in Toronto, I was commuting an hour and a quarter every day. Now I'm just 10 minutes' drive from the school, which my two younger children attend and where my wife works as a teaching assistant.
There are big advantages to working in industry before becoming a teacher. The A-level syllabus can get quite theoretical, but I can give the really heavy stuff a practical context and explain how it is used. I have gone online to show pupils the screens that traders use. That way I can explain problems using my experiences - it makes everything more relevant.
I don't see myself purely as a maths teacher. It is not my desire to be the best maths teacher in the world. I'm there to work with the kids, add value to their lives and provide a role model for children who might be otherwise lacking one.
I'm not a great teacher yet. I don't have the same expertise as someone who has been doing it for 20 years. But I'm going to be a great teacher one day.
Adam Garnish was talking to Rachel Smith.