4 days after having a Mommy Makeover, you should be able to lie flat in bed, not needing to be in the lawn chair position any longer. In my practice, the breast drains are normally removed at 24 hours and the 3 abdominoplasty drains are normally removed at 72 hours. Therefore, by the 4th day, ambulation (walking around) should be relatively easy. I recommend getting up and walking around the living room or any other room every 4 hours, and be sure to flex and extend your feet, and possibly rotate them, every hour to decrease the chance of clot formations in the veins of the calf.
Of course, don't cross your legs and don't cross your feet as you are in a hypercoagulable state this early after surgery, and venous stasis caused by crossing legs or feet could easily lead to clotting. On the other hand, post operative exercising does not mean doing push ups or overdoing it in the first 5 days or this could lead to bleeding, a hematoma and unnecessary revisionary surgery.