There is a really good exercise that I know, but it's going to be a challenge to explain.
Lay straight on the floor facing the ceiling, then have someone stand up and put their feet on each side of your ear. Lay your legs straight and then lift them up slowly together. Have the partner push your legs back down lightly and you need to control them from hitting the floor. It is a great exercise to add to your routine and you will feel a difference.
Can probably be done without a partner as well, but it gives more of an resistance.