Stop lying? (3,2)
(Other definitions for sit up that I've seen before include "It takes physical effort" , "crunch" , "Adopt erect sedentary posture" , "Abdominal exercise" , "Exercise done on the floor" .)
(Other definitions for get up that I've seen before include "Leave the bed or reach the top" , "Kit" , "gear" , "Rise (3,2) -- outfit" , "Rise and shine!" .)