Writing a book

It occurred to me today that I should have a go at writing a book.
It's just an idea, kind of out of the blue based on something someone said to me today.
I don't know whether it will work, whether I will finish it or whether it will be any good (particularly because I haven't come up with a topic yet) but I think it is something I should try.
There are a couple of topics that have come to mind and I think it will be a fiction based on real events mainly because I think that would be easier.
Another idea I thought was that I could document my experience over the last few years.
Hmmm. We'll see where this leads....