Pinterest to the rescue!
I saw this idea and it looked easy enough, so I found this old mirror frame on Craigslist
and gave it a coat of leftover paint. I then went to Lowe's and found a big, thin board that I primed with magnetic primer and chalkboard paint, and ta-da! I now have no more big, blank space, but a place to jot down verses,sayings, etc. that are on my mind.
It was a fun project! :)