The standard plank isn't an exciting exercise, but it can be a foundational one. If you can't do one and hold it for while, you need to work on your core strength.

But most coaches agree that once you can hold the standard plank for a minute or so, the exercise isn't very effective. You need to progress it, i.e. make it more challenging. The Swiss ball squeeze plank will do the trick, and you'll hit your chest too.

Swiss Ball Squeeze Plank, Standard

Swiss Ball Squeeze Plank, Elbows

The idea is squeeze the ball with the arms or elbows depending on the variation. Your core/trunk will have to work overtime due to the constant instability. You're also encouraging the spine to stabilize, building spinal endurance and a sturdy core all the way around. As a bonus, this is a pretty damn tough chest exercise.

Related:  The Best Chest Exercise You've Never Tried

Related:  Iron Abs, Healthy Spine