So my first two weeks of working out has been great. However i get really bad lower back stiffness. Not necessarily pain, but stiffness. I’m guessing its just because those muscles are so weak.
What exercises can I do to isolate my lower back and build up some strength[/quote]
Sounds to me like you lower back is getting worked fine. Are you squatting and deadlifting? That’s probably enough. I’d basically not worry about it, as a beginner, unless you’re having trouble lifting (form issues, pain). If you’re having trouble lifting it could be because your lower back is weak, or it’s overworked. What does your current program look like?