The 'Focus' extension for Google Chrome is a great way to stay on task and get chores done in small, manageable segments.
There are plenty of apps and extensions that block distracting websites from users' computers, but these programs usually assume that their user will take the hint and go back to whatever they need to do. Beyond just blocking sites, the Focus extension fills those blocked screens with an interactive to-do list, providing extra incentive to get work done.
The Focus extension is based on the pomodoro technique for productivity, which espouses working in shorter increments with breaks rather than all at once. To use Focus, one just starts a timer on the Chrome taskbar which is automatically set to 25 minutes. During that time, all pre-selected websites will be blocked and replaced with to-do lists.