So grab your medicine ball, and let's get going ... especially your lower back, certainly your butt. It's a really great core exercise. 15 more seconds, then we're all done.

Whether you're working on your deadlift PR, getting ready for a jog, or training for ( gasp!) your first pull-up, warm-ups ...

Tip: Hold a dumbbell or medicine ball for extra intensity ... This means incorporating back-strengthening exercises as well.

Directions: Add one of these exercises to the end of a strength ... reach down toward your toe with the medicine ball, and raise the ball back over your head. Keep your arms straight.