Bird Dog

The Bird-Dog is a great way to start building core stability. In this pose we remove stability points to force the core to work and balance us out to keep from falling over.
Start in all fours, hands under shoulders and knees under hips. From there brace your core by squeezing your belly button into your spine. Now reach opposite hand/foot away from your body. Hold here for a few seconds and return to all fours. Repeat 10-15 times each side.
For an extra boost of core activation, press down through your remaining hand when reaching out. This will help keep the core active throughout this pose.