Well, the biggest decision that changed my life happened before I was born
My dad, when he was around 18 or 19, wanted to go abroad. He decided he was going to apply to be an au pair but he had to choose a country to go to. He was looking down the list and saw Finland. He had never heard of Finland, didn't know anyone that had ever been and didn't know anything about it. He decided he would go there. He had absolutely no idea of the ripple effects of that decision.
He came over and stayed with a family in Nakkila, near Pori. He fell in love with Finland and kept coming back to visit as often as he could, staying with the same family who, despite the language barrier, had welcomed him as one of their own. He then decided that he wanted to come to Finland as part of a teaching EFL course (English as a Foreign Language). My mum was also on that course. At the start of the course, she had plans of teaching in the sun, lounging around on a Spanish beach with a drink in hand and somehow, SOMEHOW, my dad managed to convince her to instead come to Finland for a year. Amazingly it all worked out and they moved back to the UK after a year and myself and my sisters came along. We would go on family holidays every other year and go and see that same family my dad had originally stayed with who now had 4 daughters, 3 much older and one the same age as me. Over the years, the older ones got married and started having their own kids.
Fast forward to 2011, I was a 17 year old with nothing much to do so I was "encouraged" by my parents to spend the summer over in Finland, moving around to visit all the families that had now spread out around Southern Finland. I helped chop wood at some summer cottages and looked after a few errant children here and there. Now, this next bit can get confusing so stay with me here, during this summer trip, I went to stay with the oldest daughter of the original family. She had got married and had three kids and she thought it was a great idea for me to meet her niece, her husband's brother's daughter, who was about the same age as me and needed to practice her English. I was infatuated at first sight. Unfortunately, I was an awkward teenager that had never had anything close to a relationship so was paralysed with fear of rejection. We awkwardly danced around how we felt about each and before I knew it, she was heading off to, of all places, England for a language course in Oxford for the rest of the summer. I watched her walk off and said nothing. I had blown it. And then she texted me saying she had asked her aunt for my number and would really want to meet up once she was back from England. I very nearly had a heart attack. We spent the rest of the summer near constantly texting. I think I spent over 100€ just on texting.
So, fast forward again to get back to the original question, the next life changing decision came a bit later and was one I actually made for myself. I was getting ready to go off to university in England. I had my place confirmed, my accommodation sorted. I was ready. At this point, it was a long-distance relationship and we both lived on Skype. For the last summer before I started university, 2013, I went over to Finland to spend time with my girlfriend. Who knew when I would next be able to visit? I would have a lot of studies and practical placements to be doing so jetting off to Finland wouldn't be easy. My girlfriend had her studies to be doing as well so visiting was going to be difficult for the foreseeable future.
During that summer, I realised I couldn't do 3 years of Skype conversations. I just couldn't. It was too painful and it was killing me. Here comes that decision: I decided I wasn't going to go back home. Of course, I did go back, I had a return ticket and all my stuff was in my childhood bedroom still, but the decision was made. I was moving to Finland. Luckily my girlfriend's parents are the kindest, most supportive and amazing people ever, so they welcomed me with open arms to live with them (anyone that says Finnish people are stand-offish and reserved could not be more wrong, as my entire life will attest). I cancelled my university place, packed up and moved to Helsinki.
There is not a single second of the last 6 years I regret that decision that was almost 40 years in the making.
Kind of long, but, if I'm going to explain it, I need to do it right