I see, thanks, nice to know you made great results at 40, this makes me feel confident.
Oh, and having a teacher at the beggining will save you a lot of trouble and hard work when you will progress and your technique will be limiting to you.
While there are a lot of things we do in our life just by practice and have them written in our DNA, piano playing is not one of them ;-)
Still I hope to get somewhat good or decent with it, everyone loves to make progress and I don't see how playing the piano would result in my injuring myself, When I'l get my own piano I will probably make like an hour or half everyday, I don't see how that would result in injury, I believe injury would be for when you practice piano for more than an hour.