I work a 45 minute morning yoga routine. That seems to be an optimal amount of time for me to do some good work and find my bearing.
After warming up, the core of the routine is a modified version of the Surya Namaskara (Sun Salutation). For example, the flow for this is:
1. Start in a standing position like Mountain pose, but with hands in Namaste.
2. Stretch the arms up and out to either side (parallel to the floor) and bend forward (like a dive).
3. Move the arms in and reach down to the floor.
4. Flow into plank (push-up position: palms on the floor, elbows slightly bent and knees off the floor).
5. Flow into upward dog (knees off the floor).
6. Flow back into plank and do a push-up.
7. Flow into downward dog.
That is the start of the routine, and everything revolves around it. For example, after step 7, I perform different asanas, like Warrior I, Warrior II, Reverse Warrior, Triangle pose, etc. Then, I flow back by reversing the steps (i.e., 7 through 1).
Near the end of the overall routine, I close out with balance asanas, including Chair pose, Side arm balance, Warrior III, etc.
Once my coding day is done, I rock a 45 minute round of some other form of exercise (i.e., not yoga). I personally find that a twice-a-day routine really helps me with my cadence and outlook in all aspects of my life.
My strategy is to do sun salutations until my body fully warms up, and then do a handful of (usually standing) poses that seem like they'd feel good. It may take me 10 or 15 minutes.
More is great, of course, but even a brief session does wonders.
I often go to group yoga lessons (90 min., in the evening), but an hour and a half is a bit much for the mornings ;)
Thanks!