is my workout a waste of time?

There are so many different opinions out there on this - but honestly, a little exercise is better than none. If you want to build cardiorespiratory endurance, you'll want to increase your workout time - it's certainly a good idea - but no, even short workout are never a "waste" of time. You're still burning calories and getting your body moving.

AGREE!!

It is not a waste of time but you should try to build yourself up to 30 mins minimum a day. I have been doing circuit training for 30-40 mins at a time and it works great. You just move from one exercise to the next without any break in between. you finish much faster and get your heart rate up to burn the fat. I do not really like working out so anything to get the most out of my time I am all for it! Good Luck!

I'm currently enrolled in a fitness class for VERY MUCH beginners. Our instructor encourages us to do 10 minutes 2-3 times a day. She also says that sprinting during a commercial, walking for the next, sprinting through the next one, and walking through the last few is very helpful. Just getting up and moving is beneficial. You'll see a difference in yourself no matter what. So this is a really good place to start!

A little bit of something is better than a whole lot of nothing! You should keep it up. Add another minute every day, I bet that will make it easier for you to keep going. Also, if you don't have a lot of time you need to make time. Stop watching that 30 minute tv show and get up and exercise during it instead. This is what I have done.

You start burning fat after only a minute or two. As you workout longer you burn proportionally more fat. But since you start burning some fat right away, it is not a waste of time.

I agree that there is definite value in building up your cardio capacity with longer workouts. That being said, I hear so often that intervals are really the way to go for fat loss. Excerpt from an ariticle on Self.com:

Grunt, groan and sweat

Those Neanderthal noises you hear from the guy one treadmill over? They signal intensity, and he's on to something: You burn more fat and tone muscles in less time with gasp-inducing cardio intervals—short, go-all-out stints interspersed with stretches at a slower pace—than with a steady-as-she-goes approach. Researchers at McMaster University noted that cyclists who did 15 minutes of interval training three times a week were as fit as those who biked at a moderate speed for an hour five days a week. Imagine how trim you'd be doing 30 minutes of intervals! See for yourself: Pepper your cardio with 30-second sprints, or sign up at Self.com/goal for access to fun plans. How do you know you're pushing full-throttle? If you can talk, you're not going hard enough; if you're grunting, you're there!

I agree with the replies here, but want to add one bit of info. The body is resistant to release fat as a fuel source, hence the guideline to exercise a minimum of 30 minutes, preferably more. But, the more fit you are the quicker the body begins to use fat as a fuel. So a fit person begins to use fat as a fuel soon after beginning to exercise while an out of shape person needs to exercise for a longer time. Sounds strange, but the body assumes that you are going to do what it is accustomed to you doing. It takes a while to convince a couch potato body that it really is going to need to call on stored fuel for exercise. So if you are fit you can do a lot with just a few minutes. Covert Bailey explains this well if you care to read up. But science aside, as the others have pointed out, all exercise is good and some is way better than none. There is a lot of research out there now indicating that short interval training can be as effective as the old "long slow distance" that I grew up with.