Need a program to improve cardiovascular fitness

One of the tricks is to alternate two activities so your mind doesn't register fatigue as readily - iirc (and I don't have the study at hand), fatigue is largely a perceptual phenomenon so if you're plodding along and thinking Good Lord This Sucks...then your session is cooked. Try going a half-mile running and then a plyometric / core work stop, and alternate the two.

(as an example, one collegiate program alternates running and biking with two-man teams trading off between running and biking)

Start slow. It's a marathon not a sprint. Depending on how out of shape you are over doing it might set you back more then help.

HIIT type workouts will help. But you need to have a certain basic health level first.

On the road? Hill climbs. Stairs.

jump rope with weighted handles

HIIT will work for you.  Suicides, burpees, push ups, squat holds, lunges, mountain climbers, sprints, high knees, and etc

jump rope and HIIT

 

burpees, suicides, push ups, squat holds, walking lunges, mountain climbers, short sprints, high knees, jumping jacks, etc etc 

Cardio/conditioning is simple.

• Kettlebell swings, with sets of at least 20.
• Prowler/sled pushes/drags.

Either will increase your work capacity very quickly.
IIRC you used to be pretty fit so these shouldn't kill you. If you were a completely untrained weakling it would be a different story.

Most people won't/can't do serious HIIT every day.

If you're in reasonable shape just do wind sprints.

http://www.livestrong.com/article/311305-the-best-fitness-wind-sprint-routine/

intervals.

vary the ratios: distance/rest time/ammount/laps on-off.
2+ times a week for 30mins.
all you need is an oval or a park.
can add things in your "rest" periods like burpees or situps if you want additional benefits.
if your form sucks try running barefoot on grass 1 session a week.

Rambo, the only way to build your cardio is to do cardio, and if you're wheezing from simple exertion then it means you have to start with low-level steady state base training - i.e., easy mileage. HIIT is for those who have the base built up. However, if you really want to hammer yourself and have hills - run the hills up and down. Just don't think you're going to sprint them and get much out of it.

Now, it's worth mentioning that everyone wheezes at altitude until you adjust. It takes maybe two weeks or so to adjust to high altitudes, so don't train at sea level and expect to manage the mountains of Colombia well.

That said, check out some of the core/yoga poses like planks for off-days. Building up is an every-day deal.

It depends what you are looking for, but I have a pretty simple routine that is designed to help with cardio, muscle endurance, and power. 400 meters (1 track) at full tilt. Immediately follow with 10 burpees and 30 pushups. Without a rest, rinse and repeat (you'll probably top out at 3 the first time you do it) until you are at exhaustion. Take a 2 minute standing rest, then do it once more.

Like Thomas said, to get good cardio, you have to do cardio. Personally, I find it the most rewarding (though toughest to start) part of my workout.