What causes lower back stiffness?!

What causes lower back stiffness?

I'm 30 years old, and I am always up and doing something plenty of walking. But whenever I sit for long periods of time my lower back feels very stiff (no pain) that when I get up I look like an old grandma.

Does anyone get this? What causes it?

I'm planning to try some stretches maybe that may help have any ideas of what kind?

Ha I literally feel your pain. Stretching helps me out, but the only thing you have to do this everyday. walking is good keep it up, but make sure you stretch. If your not careful you might end up in bed like my husband. since then he stretches every single day.