A yoga workout is a wonderful thing. By doing yoga, you will see results fast, and actually have fun working out. I am not saying that you will look like a yoga instructor after one workout. However, if you want physical results fast, all you have to do is dedicate the right amount of time and effort.
The most important thing is to not buy into the delusions of the “get fit quick” mentality. If you really want to see results, ten minutes twice a week is not going to cut it. A real yoga routine needs at least three or four workouts a week. Each time you do your yoga workout, it needs to be at least thirty minutes to one hour.
By thirty minutes to one hour, I mean dedicate that much time out of your day to yoga. That does not mean an hour of hardcore workout. Putting aside an hour simply allows you enough time to do everything right. In an hour, you should be able to start with a warm up, do some meditation, do some breathing exercises, and then actually do your poses. After that, you should have enough time left over to do a good cool down exercise to finish your routine.
If you want to see results faster, I suggest doing a yoga workout as part of your daily life. Putting aside a half an hour or one hour everyday might seem like a burden to some, but just think about how much time people usually dedicated to watching television on a daily basis. If you have time to watch television, you have time to take care of yourself.
Also remember that a yoga workout is not like a typical workout routine. It is not like weightlifting or other sports in the sense that it is intense and stressful. Yoga is based around relaxation. By engaging in stretching, breathing exercises, and meditation you gain much more than just physical benefit. You gain mental, emotional, and perhaps even spiritual benefits as well.
I suggest joining a class or even finding a good book or video to help educate yourself on doing yoga. While an instructor is perhaps the best resource you can have, finding a good book or DVD is good way to do some independent study. In my opinion, you should have the ability to consult both. Remember anything worth doing takes some amount of time, but also remember that with yoga you can see faster results.