“Why did you want to be a teacher?” I hear this question regularly from family, friends, pupils and even strangers.

Everyone has their opinion about teachers. Whether it’s the constant teacher bashing about how easy it is finishing at three o’clock and having so many holidays, or the “I don’t know how you do it” brigade, most people like to comment as if they are experienced educational professionals themselves.

So why did I become a teacher? Recently, I gave this more thought as I was preparing to give a speech to my leaving Year 11s and it was harder to give a coherent answer than I anticipated.

You see, I wasn’t one of those teachers who knew this was their goal since they were old enough to tell someone to sit down in a teacher voice.

The first reason I could think of was because of my granddad. As I was growing up, he volunteered at local schools, helping children learn to read. Leading by example, his core values of a strong work ethic and desire to help others had a profound influence on me and I worked on a similar volunteer scheme as an undergraduate student.

My aunty was also an excellent teacher, until she had to take early retirement owing to ill-health. Along with my parents and other family members, she played a huge part in pushing me to be the best I could be, which is a sign of a great teacher.

Secondly, every pupil remembers their favourite teacher. I was a run-of-the-mill student who achieved very average grades, but I remember the significant influence my favourite teacher had on me.

He was charismatic, witty and engaging and he encouraged me to go through sixth-form and then onto university. Without him, I doubt I would have continued my education. On a subconscious level, I think I always wanted to imitate Mr O’Connor and change people’s lives like he had changed mine.

I think I finally decided on my vocation while I was reading The Seven Habits of Highly Effective People by Stephen R. Covey. The author asks you to picture your funeral and think about what you would want to be remembered for. This was what prompted me to train as a teacher, as I believed it would fulfil my need to make a contribution to a community.

At my funeral, I want to be remembered for making a difference to people’s lives. I had decided this was my life goal, my mission statement, and education would be my tool.

Maybe a lot of teachers can relate to my journey. Maybe they have other reasons for choosing to be a teacher. However, what I do know is that every teacher has days when they question if they made the right decision.

With so many either leaving, or considering leaving, the profession, what is the incentive to stay? It certainly isn’t the excessive workload, performance management and constant government meddling.

Four years ago, I left the UK very disillusioned with my choice of profession after suffering severe anxiety and panic attacks. I went from being a fresh-faced, confident and determined NQT to a nervous wreck within the space of a few years.

I moved to Madrid in hope of a more teacher-friendly system in which I could once again flourish as an educator. I found a school that teaches both the British and Spanish curriculums, and the attitude towards education felt like a weight had been lifted from my shoulders.

Gone were the days of constant scrutiny, GCSE targets and blaming teachers for pupils’ failure. I found a culture where pupils were eager to learn and teachers were trusted as professionals, which was extremely liberating.

However, I felt like I had sold out on my mission statement. After all, I believe most teachers would be able to come into this middle-class suburban school and succeed with the calibre of pupils at their disposal. How was I going to make a difference?

Fast forward four years and I am just about to make my speech to the leaving Year 11s. Just as I was about to speak, I realise exactly why I became a teacher, and it was for moments like this. To see their academic and personal progression over a period of time is such a privilege, which I expressed to them.

Sometimes we are too busy trying to influence them, we don’t realise the impact they can have on us.

A few days later, one pupil said, “I want to study computer science because of you”. Another pupil said I had changed his attitude towards education and he remembered what I had said in my first lesson with them four years ago.

Now, I realise children sometimes say things they think you want to hear, but he genuinely quoted me word for word. I felt like my mission was alive and kicking. I was making a difference, just in a different way to teaching in the UK.

Two days later, I received a Facebook message from a pupil I taught while I was in the UK. Unbeknown to me, this message had sat unread in my inbox for two years. The message had the same three words “because of you”.

“Because of you, I finished sixth-form and I am now starting a job and I wouldn’t have done it without your help.” Had I had the same impact on this pupil that my teacher had had on me years earlier? I couldn’t think of a more fitting way to say thank you to Mr O’Connor for helping me see my potential and inspiring me to make a difference.

You would be hard-pressed to find another job with this level of satisfaction. After eight years of teaching and an abundance of highs and lows, I have the joy of seeing the progression of my mission. I am making a mark on the world in my own unique way.

When a pupil says those three little words every teacher wants to hear, it’s a reminder of why I started, which is all the incentive I need to continue.

Thomas Slack is a teacher of computing and key stage 3 coordinator at The English Montessori School in Spain