We break up the exercise into three components: cardio, strength and stretching, they are all equally important for your body.
The best way to do it is to break up the exercise. Cardio needs to be done everyday or at least six days a week and the strength and stretching you can do two to three times a week.
Cardio is great for you cardiovascular system, your heart. Cardio is what really helps you lose weight by burning those calories.
The routine that I've used in the past and am trying to get back to is walking everyday, a weight routine at the gym at least 3 times a week and a pilates or yoga workout 3 times a week. I have DVD's and that is mainly what I have to use in the winter when walking isn't an option at -40°C. I have several cardion workouts from Walk Away the Pounds to The Biggest Loser. I also own an elliptical machine that is a great workout as well.
So find out what works for you and start slowly. Do 10 minutes increments if that is all you can work with. I know it's hard when you are busy with house and home and family. Just do what you can. You can do it!
Another thing to do it get the family involved. My kids love doing yoga. We all love going on family hikes and walks, the scenery around here is to die for, so it makes the walks so much fun. We dance around the house and play at the playground. They even managed to get me to go down the giant slide at the park. We all love going swimming. So we made it fun!