Chicks - So glad your here, it's a great place to be.....
First off - Regarding what is enuf exercise? Something is better than nothing, don't let anyone tell you otherwise..
How much you have to do to increase your level of fitness depends on where you are when you start.

You have to start somewhere, even if it walking around your house during commercials
The brathing tapes do work, becuz it increases the oxygen to your muscles. I'm not bragging, but I have been working out for 34 years and some of my favorite and most effective tapes are 7 - 15 minutes. It's not how long you work out it is how consistent you are. To see improvement in your body it takes time. If you are lucky you will grow to really enjoy your workouts and then it will become a habit, you'll actually feel bad when you miss a workout.
As for not having time to workout, you have to make time. For me, that is first thing in the morning before work. Which means I have to get up at 4:45 a.m. to be at the gym by 6 a.m. I workout and get ready for work there. By 8 a.m. I feel wonderful and plus my workout is done for the day
This is all JMHO, don't mean to sound like a know-it-all
Oh , the other plus is that if your on a heathy eating plan and workout routine your improved body results are much better than just doing one or the other.
Okay I'm off the soapbox