Sometimes the biggest challenge for writers is figuring out how to motivate ourselves to write. Luckily, there are a lot of apps and strategies that can help.
750 Words encourages you to write at least 750 words a day. You type directly into a page at the website; you can then export it to your word-processing software. Your writing is private, but you have the option of publishing your word count via social media. The site tracks your producivity and even makes it possible to keep track of other aspects of your life (movies you have seen this year, for example) if you wish it to.
The Pomodoro Technique relies on using segments of timed writing (using a tomato-shaped kitchen timer, perhaps) to structure and advance your writing. Focus Time is a fun app that works with the Pomodoro Technique. Instead of using a kitchen timer, this app helps you to work for four twenty-five minute sessions (with a short break between each segment), followed by a longer break at the end. The app also presents you with statistics on your writing time. There are a lot of apps that allow you to use some version of the Pomodoro Technique (though you can just as easily use a low-tech kitchen timer).
Scrivener is a content-generation tool for novels and other long documents. It helps you organize and develop your content and it keeps track of your research. It allows you to look at your work in many different ways and even manages drafts.
NaNoWriMo offers resources and community, especially in November.