I'll chime in with something that might help somebody down the line. I have always done weight training, running, biking, like a lot of people, and I learned the hard way about the importance of training your gluteus medius. Just doing heavy squats, leg press, biking, etc, all in a straight line develops your maximus, but what happens when your medius isn't firing properly, because it's lagging way behind in conditioning, and then you find yourself in a job where you sit a lot, your stabilizing muscles in the pelvic region get unbalanced and your pelvis will slightly shift(for a lack of a better explanation). At first this will cause some dull lower back pain and while you search for what's wrong, even talking to a doctor, you will be led down a path to nowhere. If you don't start training your gluteus medius, you could end up like me, in debilitating pain. I'm talking about laying on your back and can't even roll over to get out of bed. Once I got all this figured out, I started training my medius and gaining back my mobility in my pelvic area and my issues are gone, including lower back pain. I now have a weekly routine outside of regular leg training just for that because for about 2 days I wondered if I was going from completely mobile to being an invalid.
Things like yoga and leg abductor training really help. For more insight go to Youtube to get the exercises. It's all quite easy and actually feels really effective as you do it, which helps.
When I was 25 and just hitting the hard weights I would always see people in the gym doing weird stuff, and I would roll my eyes. Now I get it.