If you had asked me three years ago if I would ever go vegan, the answer would have been a polite but firm “no”. I would have told you how I could never give up cheese and how I worried about a vegan diet being healthy. I knew that they weren’t the strongest nor the most informed of reasons, so I would have added that I only bought meat when I could afford to buy organic and British, and always bought free-range eggs. I would have wanted you to know I was informed about what was “good” or “bad” farming practice, and I shopped accordingly.

I had been a vegetarian on and off since I was a teenager, and cared deeply about the planet. I recycled diligently, carried a reusable water bottle, signed petitions to address the climate disaster and joined protests. I bought cruelty-free makeup, was fervently against animal testing. I was a conscious and conscientious shopper and consumer: I considered the planet when I made choices.

For almost my whole life I had been concerned about the planet. As a child, I’d lecture my hairspray-wielding nan about CFCs; in primary school I held a bake sale to raise money for the RSPB, the British bird-protection charity, after the Shetland oil disaster in 1993. I was mindful of the environment, and proud of it.

Just not mindful enough to make a huge lifestyle change that would be disruptive. Even these days, veganism is frequently inconvenient in that you are always having to check packaging (items you think are safe may have changed their ingredients), trust other people when they are preparing food for you and check everywhere you go in advance for vegan options.

So how did I end up a vegan? It all started when I met my friend Sophie’s partner, Rey. We were having a barbecue in Burgess park in south London, and Sophie and I had to wait to eat because Rey and his friends wanted to cook first as they were vegan. They weren’t righteous or aggressive about our food choices, and we didn’t roll our eyes or make jokes about theirs. We had a nice day out.

When Sophie and Rey announced they were expecting a baby, she told me she was going vegan, and would raise their child as a vegan. I’m embarrassed about it now, but I was concerned – all my knowledge of veganism came from random snippets of internet lore. What about calcium? What about protein? What about vitamins? Wasn’t it dangerous? Sophie very patiently told me what she knew, and directed me to look things up for myself.

So, I did; visiting websites, reading leaflets, watching documentaries and filling in the gaps of my knowledge. What I learned started to stick: I became vegetarian again, lapsed and then went back to it. I couldn’t reconcile what I had learned about the realities of the meat and dairy industries with the person I believed myself to be. I asked Sophie – for the first time – why she decided to become a vegan. She wasn’t like me, a so-called advocate for the planet and animal rights. In fact, she was probably the last person I’d expect to become a vegan. “Because I don’t need to eat meat, eggs or dairy,” she told me. “Things don’t have to suffer or die for me to live well.”

That was the moment it clicked. Consuming meat and dairy was admitting I was OK with animals suffering and dying for my pleasure/convenience/survival. But I could choose something different. So I did.

I became vegan two years ago. Of course, I am in a position where being a vegan is easy: no food allergies or relevant health issues, enough money to buy speciality vegan ingredients to liven things up, no dependents, time to cook. The impact that it has had on me has been huge. I have seen an improvement in my overall health – an unexpected benefit; tighter friendships with vegan friends (it’s the new smoking in terms of social connection). Before I became vegan, I was never much of a cook, but now it has become a hobby. I love experimenting and finding ways of “veganising” food I used to eat.

More than that, it has begun to change every aspect of how I live as I try to always minimise suffering, and do my best for the planet. I am lucky to live in a town with eco-friendly refill shops. I have started making my own body moisturiser, cleaning spray, laundry detergent and “toilet fizzers” to cut down on disposable plastics and chemicals. I question where things I buy come from: who made them? How did they get here? How long will they last? I am trying to be a better consumer, even if it is inconvenient sometimes.

In the end, what it came down to was having the courage of my convictions to embrace veganism. Now I am proud to be walking the walk.

Hold Back the Tide by Melinda Salisbury is published by Scholastic in March (£7.99). To buy a copy for £7.03 with free UK p&p for orders over £20, visit guardianbookshop.com or call 0203 176 3837