I'd like to mention News Feed Eradicator here - not only does what its name implies, but it adds a motivational quote in the empty space. The quotes are usually

I'd like to mention News Feed Eradicator here - not only does what its name implies, but it adds a motivational quote in the empty space. The quotes are usually about goals, procrastination, etc and it's saved me a lot of (potentially) wasted time.