In the last few months, my legs have started falling asleep when I sit on the couch or chair because the cushions have flattened to the point that the frame hit the back of my knees. It quite literally cramped my style when I wanted to spend hours grading and watching movies.
A week ago, I ordered a 10-foot roll of 2-inch foam for $35. It arrived Tuesday and it took about an hour to cut it and put it in the cushions. The couches look renewed, my legs aren't numb, and my fingers are crossed the the furniture will hold out for another year or so. At that point, I think we'll shell out a little more and buy new cushions since the frames and upholstery are still in great shape.
I'm pretty proud of myself for figuring out how to make the couches a little more comfortable!