A Side Plank
One of the many exercises you can use to strengthen your abs and core is the plank. Planks can be done in many varieties and levels. When working on side and hip strength, the side plank can come in very useful. How to do a side plank:
1 * Lay on your side, lengthening your entire body into a straight line
2 * Prop up on your bottom elbow, and rest your hand on the floor
3 * Keeping your body as straight as you can from foot to shoulder, lift your hips straight up towards the ceiling
4 * Hold the pose in the high position for a length of time, with your abs pulled in, core muscles compressed and make sure that your elbow on the floor is in line with the shoulder joint.
5 * Slowly lower your entire body back to start position
While lifting and establishing your balance and the hold, you can challenge yourself even more by stretching your top arm up to the sky in a straight line. Do these several times in a row, and don't forget to do both sides!