I cannot do the position Vajrasana or rock pose. It is very painful to my knees. Is this normal? Can this pose be attained with practice? I have tried sitting on a block or towel.
Please, be careful when practicing rock pose, not everybody can do it. You can use a cushion or a block, to help you. Also, apply a ointment in your knees to help with flexibility. Turmeric is also excellent for the joints.
Be patient and keep trying.