Wind Sprints!

Gyms and machines are great for heart building cardio but I suggest you add a dose of outdoor "old school" wind sprints to your fitness routine.  Essentially just short dashes back and forth (or along a circuit) wind sprints are a great, quick way to get winded on a daily basis.  

To quote the great Gary Player (a professional golfer who was way ahead of his time in the 1950's with an athletic approach to a sport that was largely viewed as skill):  "Whether it's climbing stairs in your house, riding an exercise bike or jumping rope, the key is to get at least slightly out of breath for 10 minutes.  It's practically impossible to be badly out of shape if you do this each and every day."  (I love that last part!)

While you can do these anywhere, I prefer a natural grass surface for cushioning and the slight variations in surface which enhance your balancing skills.  Natural athletic fields are great.

Just simply take off and run, jog, or sprint to in a series of intervals.  Simple back and forth sprints with a short break in between is easiest.  *This is something you need to adjust to suit your own needs and fitness levels - START SLOWLY AND BUILD UP!*

I've always felt like being able to make a quick sustainable dash is not only a great measure of your fitness levels but also an essential life saving skill!  Just remember to start slow and build up!