There is a lot of confusion nowadays about cardiovascular (endurance) exercise. Some people will say that it is the be-all and end-all, whilst others say that we don't even need to do it at all. And as is often the case, the truth is somewhere in the middle.
There is no doubt that our bodies are made to move. We are not designed to be anywhere near as stationary as we are in our modern lives, and as a result we now have to actually work hard to achieve cardiovascular fitness (which would have been part of daily life for our ancestors). In fact I read one study recently that said that even our country cousins on the farm are now not getting enough daily exercise since the advent of modern machinery.