The plank is a great move that targets your core (abdominals & lower back).
To properly execute the plank...
1. Get on your hands & knees (your hands should be positioned under your shoulders, not out wide as in a push up)
2. As if you were to go into a push up, extend your legs to where you are now balancing on the tips of your toes
3. Keeping your body in line (neck & spine neutral, bottom down, back not arched), focus on tightening your abdominals to hold the position
4. Don't forget to breathe
If you are a beginner, try to work up to holding this position for 10 seconds. Once you master 10 seconds, move on to 20 & so forth.
For those of you that need more of a challenge:
~ Try holding this position for 1 minute
~ Do toe taps (start on the right side & bring your leg out to the side, tap the ground with your toe, return to starting position, & tap with your left leg...do 10 reps / 5 on each side)
~ Try "rolling T's": begin with a plank and "roll" to your left side, while keeping your body up, don't drop to the ground. The left arm & left leg will be touching the ground, stack your right foot on the left & reach to the ceiling with your right arm; return to plank; "roll" to other side.
Don't get discouraged, the plank is a very challenging move. Try to work up to a higher level than where you began. As long as you stick with it, you will see progression & be amazed at what your body can do!