Walking – is one of the best exercises you can do, its low impact on the joints and less stress to your body, but one thing, you must walk at a fast pace to get better benefits to your circulatory system for at least 30 mins to an hr per day. (American Council on Exercise Recommendation) FYI… We were made to be active/physical all day and really its not enough to do just a little activity during the day but all day.
Next on the best Cardio to do is elliptical machines – its rotates in a elliptic circle causing you not to have a lot of stress on the knees or you can use the stationary reclining bike which is another low knee bearing cardiovascular workout machine.
Now! mind you, these suggestions are for people who want the cardio benefits without the joint pain that can come with the harder machines.
Just a reminder, start out slowly and build up the intensity in your cardio routine, and begin with 10 mins and increase it slowly as you get stronger and your breathing becomes easier.