But until that point - well, it's hard. I don't mean hard like going down a mine everyday is hard, but it is hard to persist when no one else is taking your writing seriously. When it's called 'your little hobby'. When I was on the MA at Bath Spa, several of my fellow students confessed that their motivation for doing the MA was in part to have justification for spending time writing. They were dreading when it finished and partners/work colleagues stopped giving them the space they needed.
I think the only solution is to become as sneaky as possible. Don't tell people you're writing a novel, and you don't get asked ''got a deal yet?', which is infuriating when you haven't yet finished. At home, if you have partner/children around, slink off to your writing space and grab whatever time you can. Don't ask it's okay, because that will just alert them that you're going, and you'll never get away. Learn to adapt to your circumstances - a writer can't be fussy about the space they write in. Write whenever and however you can.
And if your neighbour does ask about 'your little hobby', stamp on their feet, hard. It may not make you the most popular person at the party but you will feel miles better. And next time, don't tell them that you're writing.