I would recommend the short story form, which is a lot harder to write since you have to be so careful with words, until there is plenty of time to doodle through a novel.

You can write a short story in two hours. Two hours a day, you have a novel in a year.

A short story is one idea; a novel is a whole soup of them.

I wasted a lot of years working on my writing and very grandly saying, 'And now... My Novel!,' which would soon be reduced to a short story, then to a paragraph.

A short story is the shortest distance between two points; a novel is the scenic route.

What greatly annoys me is sometimes you see the short story being described as a training ground for the novel. Kind of like an apprenticeship. And in lots of ways, it's a far harder form.