Many of us at one time or another experience stiffness of the back and tightness of the hamstrings. The Cat-Cow and Downward-facing Dog, are two simple stretches that can be extremely beneficial in loosening up the posterior chain.
Perform each stretch 30-60 seconds prior to starting your day, and your workout. Be sure to intentionally engage your core throughout these movements.
Remember to breathe deeply and ALWAYS work within YOUR pain free available range.