I have ALWAYS hated cardio with a passion, and have never included it in my exercise program. And by cardio, I mean what most people think of as "cardio"-running or doing the elliptical, for example, for 45 minutes or however long. That type of cardio completely BORES me out of my MIND, and I don't think it's really the most effective way to get in or to stay in shape.
Most women do WAY too much cardio because they think that's what they have to do to lose weight. I see it at the gym every single day-all the women are on the ellipticals, while all the guys are in the free weight area. And if a woman is lifting weights, she's usually just doing 5lb dumbbell curls or working her abs. That's why they stay fat or just skinny fat-I'm just sayin, it's true!
Let me tell you, you will get much better results just being on a good strength training program and by eating healthy, than by doing an hour of slow, steady state cardio every day. Actually, too much cardio can work against you by causing you to lose muscle, which therefore slows down your metabolism. Excessive cardio can also increase the stress hormone, cortisol, which will cause you to gain fat. The absolute best thing women can do for themselves is to lift weights and build muscle. I will say it a million kazillion times!!
Instead of traditional cardio, I think that doing short, more intense conditioning workouts is a much better way to go. The way I have always done my "cardio" is by doing just 10-15 minutes of jump rope intervals, running stairs, or running sprints, either after my weight training workouts or on my off days.
You could also do bodyweight circuits consisting of exercises such as burpees, lunges, squat jumps, mountain climbers, and bear crawls, just to name a few. For example, pick 4-5 exercises and do each one for 20-30 seconds as hard and fast as you can, then rest at the end of the circuit and repeat 3-5 times, or for 10 to 15 minutes total. Short and sweet, but intense. I'd MUCH rather do something like that for 10 minutes, than to spin like a hamster on a wheel for 45 minutes! You could also incorporate things like kettlebell swings, dumbbell or barbell complexes, flipping tires, and sled dragging/pulling.
Many people think that the only way to keep your heart healthy is by doing traditional cardio. But that's not the case. Anaerobic traning(weight lifting, sprinting, jumping, etc.), has also been shown to benefit your heart. And it comes with the added benefit of building/maintaining muscle mass, which is always a good thing. Higher intense exercise also burns more calories and keeps you burning those calories hours after you stop exercising, something that steady state cardio does NOT do. Plus, it's just more fun! (Well, to me, at least!)
Here's an article to check out about metabolic conditioning and aerobic vs. anaerobic exercise: http://www.crossfit.com/journal/library/10_03_metab_cond.pdf