Why Conditioning Isn't Just Cardio

Conditioning is one of those words that gets tossed around a lot to mean one thing, but in reality, it means so much more. 
For many people, when they think "conditioning," they think cardio. This could be in the form of LSD (Long Slow Distance) jogging, interval training/sprints, skipping rope, etc - activities that get you breathing hard and sucking wind.
"Cardio" entails cardiovascular and cardio-respiratory conditioning, or, in other words, the ability of the heart to efficiently pump blood through the body, and the lungs to efficiently take in oxygen and discard carbon dioxide.   If you're not sure what this is, go outside and sprint to the end of the block and back as hard as you can. Go ahead - I'll wait...Great, you're back. Are you breathing hard? Thought so. This is cardio.
However, that is only one element of overall conditioning.
Next, there's muscular conditioning. This is the ability of a muscle (or group of muscles) to contract repeatedly over a given period of time.  If you're not sure what that means, hit the floor and do as many pushups as you can. Go ahead - I'll wait again...how was that? Likely you're not breathing as hard as you were from the run, but your arms and chest are probably burning pretty bad - much more so than your legs were from the sprint.  That's muscular conditioning.
Then there is strength/power conditioning. This is sort of the next step after muscular conditioning. Now, instead of your muscles just having to contract repeatedly (were the amount of force they have to produce isn't an issue), they'll have to contract at near maximal force repeatedly.  Or, in other words, how many times (within a given period of time) can you lift a weight that's really close to your maximum?  
So, if repping out on pushups was muscular conditioning, loading the most you can bench press onto the bar minus 15% or so and doing as many reps as you can with that would be a measure of strength conditioning.
And along those lines, a power-based movement (say box jumps) done for max reps would be a measure of power conditioning.
To have complete conditioning, you must train all these elements - not just cardio, as many people would think.