Who needs to sit?

Rebecca is still not sitting up by herself for more than a few seconds at a time. She doesn't really show much interest in it. She is perfectly content to lie on her tummy on the floor and play.

I've tried using the Boppy pilllow to encourage her and get her used to being in the sitting position...but who wants use the pillow as a support tool when you can lean over and play with the tags on it? :)