I once saw in a drama a girl who had to practice piano on a keyboard drawn out on a piece of cloth and now I read about a man in prison who taught himself piano from books and practising on a cardboard keyboard. It is amazing to read about such determination. I do not think I can do this. Absolutely full of respect for this man.

http://www.newyorker.com/culture/culture-desk/my-cell-learning-to-hear-on-a-cardboard-piano

I once had an adult piano student who went from zero to grade 3 and Alfred adult piano book level 3. She has unfortunately stopped learning when she moved to another town for work. The other adults who came my way did not go past Alfred Book 1. Now I am left with just one adult student, whom I hope will have the will to go as far as she could.

Here's an article about adults taking up musical instrument.
http://www.bbc.com/culture/story/20140709-never-too-late-to-learn?ocid=ww.social.link.email