As an oil trader, I sit at my desk 12 hours a day. This has caused me to have lower back pain, however I have developed a cure!! Just perform these 8 Bikram yoga exercises 3 times a week, roughly takes 20 -30 minutes each time. Do each exercise 3-5 times holding for 10 seconds for beginners all the way up to 20 plus seconds for the more advanced.

First simply stand and up and breath in through the nose to the count of 5. Then exhale to the count of 6. Repeat 5 times. This is a Mindfulness exercise, and prepares you mentally to perform the exercises with the correct form and timing.

Here are a selection of Bikram yoga exercises which I think are particularly beneficial to the lower back. I have taken the pictures from bikramyogabethesda.com, there are many similar sites which explain the exercises in more detail.
Awkward Pose

Seems awkward and pointless, but it really strengthens your knees and loosens your glutes.

Then next 3 exercises simply stretch your back in the opposite direction to the slouch forward position you have sitting at a desk all day. SIMPLE!!

Cobra Pose

Full Locust Pose

Locust Pose

Sit up

If the Sit Up pose is too easy try the Head to Knee pose or do both!
Head to Knee Pose

Camel Pose

I like this exercise as it improves balance and you can vary the pain level from little to a lot.

Standing head to knee Pose

And thats it. Enjoy