One of the better abdominal exercises that not many people do are side planks. Start by lying on your side, legs together, feet stacked. .Bend your bottom arm and make sure your elbow is underneath your shoulder and place the other hand on your hip. Use your abs to elevate your hips and hold at the top. Start with whatever you can do and work your way up to 1-2 minutes. This is a great exercise to hit your obliques without putting much stress on the spine.