It's a good exercise that can give you some peace. Really it can work.
If there is someone that you live with, work with, come in contact with and they simply drive you nuts...try to find one good thing about them and let that be your focus. Let the other stuff fall away.
The other stuff is NOT bothering them but it's driving you nuts. So you need to change your focus if your contact with them needs to continue.
Here is an example...when I worked in TV there was a director who drove me nuts. Every time I worked with him he simply drove me nuts. He complain..nitpicked...made me do things over and over.
Then when day I decided there must be something good about him I could focus on. I thought "he is breathing!" Then my head said "he is taking up air someone else could use!!!" Apparently NOT my answer. :) LOL
Then I did put some thought into it because I was tired of being irritated. I decided that he really cared about his work. Really cared and was doing the best he could to make it good. Honestly that day my attitude and behavior towards him changed. Funny thing...I calmed down and so did he. It wasn't all delightful...but the fireworks stopped.
So who is driving you nuts...and what's one good thing about them?