Another thing I've started doing that works for me is removing a page from the history on my browser. It's easy to mindlessly browse something like reddit when I can just type 'r' and hit enter because the browser autocompletes sites in my history, but even the 1 second it takes to type out 'reddit.com' gives my brain time to realize there's nothing in particular I wanted to look at, and I was just going there out of habit because I was bored.