Motion is described as 'helps you stay productive on your computer by reducing time wasted on distracting sites and improving focus on the tasks you've set out to finish'. There are more than 50 alternatives to Motion for a variety of platforms, including Mac, Windows, Android, iPhone and Google Chrome. The best alternative is LeechBlock, which is both free and Open Source. Other great apps like Motion are Cold Turkey (Freemium), Forest (Freemium), FocusMe (Paid) and Freedom (Paid).
LeechBlock is a simple free productivity tool designed to block those time-wasting sites that can suck the life out of your working day. All you need to do is specify which sites to block and when to block them.
Freedom is an application that disables networking on an Apple computer for up to eight hours at a time. Freedom will free you from the distractions of the internet, allowing you time to code, write, or create.
SelfControl is a free and open-source application for Mac OS X that lets you block your own access to distracting websites, your mail servers, or anything else on the Internet. Just set a period of time to block for, add sites to your blacklist, and click "Start.
Focus is a Mac app that blocks distracting websites (like Facebook and Reddit) and applications, so you can improve your productivity. It has lots of awesome features like scheduling, showing motivational quotes on blocked pages, whitelisting and pomodoro support.