What is a good beginner cardio workout?

I need to change my routine up. I am on the treadmill 4-5 times per week 40-50 minutes and I am doing the Bender method for my abs 5 days per week. I think my body is getting used to this and need to change things up. I dont have time to go to the gym so I need something at home. Any suggestions would be really appreciated!

P.S. It must be beginner as I am about a month into this whole workout thing again.

Re: What is a good beginner cardio workout?

What are you doing on the treadmill? I would suggest increasing the intensity and/or doing interval training.

Re: What is a good beginner cardio workout?

I am on for about 50 minutes per session about 4-5 days per week. I initially was goingat a pace of 4.0 for about 40 minutes and warming up/down the other 10. I have the incline at about 7.0. Lately, I have been increasing the intensity to about 4.3 and the incline to 9 or 10 and then increasing the rate to 5.0 intervally as I am not the best runner. I am working on that. I was looking to change my routine so that I had the treadmill 2-3 days per week and the cardio workout 2 days per week. Any suggestions?