I found a very easy way to do this all you have to do when it tells you to get on the ground is sit down on a chair or sofa then when you start your push ups just lift on leg up a little more then stright out then back down and just keep repating this you can also do the same thing just extend your arm stright out in front of you and just keep lifting it up and down or you can always do girl push ups but I found sitting down much easier.
Edit - With the new update you dont need to do anything just make a custom work out with push ups and lets it run don't have to do anything just like the warm-ups