Most folks know that they should be doing some sort of cardio workout plan.  It can help to reduce bodyfat, improve heart function, and keep the lungs in shape.  It can, as with most exercise, also be used as a form of stress relief.

However, most folks also just plain hate running.  And in many minds, cardio = running.  Ugh.

Good thing this isn't the case.

A good cardio workout plan, while it certainly could involve running, has no direct need for it.  To improve cardiovascular function, all the cardio exercise has to do is simply get the trainee breathing hard.  By doing so, this inherently means that the trainee's lungs are working, and one can't be breathing hard without an increased heart-rate, so that means the heart is being worked as well.

So, put simply, breathing hard = cardio workout.

It doesn't matter what kind of activity you do, it just matters that you are breathing hard when you do it.  It can be running, cycling, rowing, etc.  It can also mean a variety of sports like playing soccer, basketball, wrestling, or marital arts.

If all of these are such good cardio workout plans, then why do so many people run and use gym machines?  Simple - it's 'dead-head' work.  Just get started, and put in the work.  No real thinking is necessary.

Does it work?  Sure, as long as you do a lot of other stuff right as well (to include diet, a strength training program, etc.).

However, there are a lot better ways to accomplish the same thing.  This can include the aforementioned playing sports, various forms of weight training, or some simply physical/manual labor.

Whatever sort of cardio workout plan you choose, above all else, just make sure you're breathing hard while you do it.  The rest will take care of itself.