Basically, if your heart isn't strong, your body isn't strong. So cardiovascular fitness is geared toward making this most important muscle stronger!
I served 8 years in the US Navy after high school, so I did plenty of cardio back in the day - running, jumping jacks, 8-count body builders (which I believe were invented by Satan himself!), sit ups & push ups.
But now that I am a fat & happy civilian, I prefer to get my cardio by going for a brisk walk. I learned that cadences are a wonderful thing. When I ran in formation with a cadence caller, I could run forever. Going out on my own is a different story. So I downloaded an entire album of Navy cadences onto my iPod that I use for walking. Since it's geared for running (which I don't do anymore - unless chased by zombies) I really have to hit a fast stride to keep the beat. And we happen to have a nice park with a 1.6 mile paved path around it at the end of our street.....yay! I use the 1 1/2 block walk to get to the park as my warm up & cool down.