Looking past self-perceived topic saturation

I've got a question for bloggers. Basically, how do you get motivated to write about things that have already been written about? Or rather, how do you not get demotivated when you know other people have written similar things before?

My wife is constantly telling me that I've got so much perspective on so many different things, and that I should write my thoughts about stuff on a blog. The problem, in my mind, is that most of these thoughts are things that I've picked up from other people's blogs, tweets, YouTube videos, etc. Even if I would be able to say things differently or combine multiple ideas/thoughts together, it's really hard for me to bring myself to write about something that I feel has already been written about before.

Do you ever feel this way, and if so, what do you do about it?