When I first did vajrasana, I had a hard time getting into the pose because I have such bony joints. I actually felt my ankles and knees digging into the floor. To solve the problem, I placed a thick towel on the floor.
When I try to switch to Varasana pose, I have to place a cushion below the butt because I can’t sit the butt all the way down. Some people prefer to use a bolster because it feels pretty comfortable when you lie backwards. Take care of the hips if they feel tight. Never force yourself into a pose if you feel any pain in any part of your body because you may injure yourself. If you practice each day going at your own personal maximum, you will find that you will slowly gain flexibility as the days go by.