Lie on your back with one knee bent and foot flat on the floor. With the opposite leg out straight point the toes.
Then, whilst raising the leg up straight, gently pull the toes towards you (pushing the heel towards the sky). Continue until you feel a slight pull in the back of your hamstrings, calves or bottom then bend the knee again as you point the toes away from you.
Slowly and in a controlled manner, lower the leg whilst pointing the toes.
Hover a little from the bottom so as to not rest, then raise once again, pulling the toes towards you.
Repeat 10 times on both sides.
Please note that this is a sciatic nerve mobilisation and so you do not need to hold the stretch or force it. You are simply nudging the nerve a little. Remember that when the leg is lowered you point your toes and when it is raised you pull the toes towards you.
Mobilising an already irritated nerve can make things worse so if you have sciatic symptoms this may not be the best exercise for you.