Easiest to Implement Most Useful Advice Ever

I read a paper "one last time" last week before sending it to a journal. I found and fixed a few things but thought it was generally good to go. Then I remembered reading some advice on twitter about how having Word (or some other program) read your paper out loud to you is a better way to catch mistakes. I tried it, and it worked! I found a bunch of missing words that way! How is possible that we miss these things when reading? Did you notice that I missed the word "it"?  

I didn't know Word knew how to read documents aloud, and I especially didn't know it was such an easy way to catch your own mistakes.