Baby burrito doing sit ups

You can't tell from the photo, but Astrid is doing a partial sit up. I see her doing this more often each day. I can tell her muscles are getting stronger because she wasn't able to do this a few weeks ago (without grabbing onto something).Also, now when she rolls over onto her tummy, she can roll back over onto her back again. I see her moving her arms and legs when she's on her tummy and she's now able to raise her bottom in the air. It's just a matter of time before she gets the movements coordinated, and her muscles get strong enough to start crawling.