I never meant to invest, but it hearkened almost incidentally.
See, I always saved up since... Well, birth, really. Whenever there was an occasion (birthday, Christmas,...), half of what my grandparents gave went directly in that saving account.
I only got access to that on my 18th,but by then I was used to live quite sober.
Even when I started working, I hardly changed my habits. There were months I saved almost half my salary. Never got a car, have no expensive hobbies.
... And then I bought my apartment. As a result of this behavior, the mortgage was relatively low (and my parents wouldn't want to lend it to me, or it would've been paid back by now). It'll end at the end of 2022.
So when I met my girlfriend and she wanted to move (after living with me for 3 years), I made it clear I was NOT going to sell my home. So I searched and found someone to rent from me.
While it has some responsibilities, he's basically paying off my mortgage and still providing around 150 euro per month profit. Which will be 650 per month in a couple of years (Or more, if inflation kicks in).
So... It certainly turned out a good investment so far,and I could probably make even more of I sell the apartment for a profit. But that was never my goal.