That sounds good as far as cardio goes. The important thing is to get your heartrate up. However, for losing weight, it's also important to incorporate strength training. Lifting weights burns calories, and your body will KEEP burning calories after your workout for several hours, whereas if you do cardio only, your body goes back to base metabolism very soon after your workout. Also, building muscle means you will be burning more calories while you're at rest or going about your day, so it is important for fat loss. Contrary to popular belief, it is really difficult for woment to build big muscle, so don't worry about bulkin up. You'll just get toned and firm up with weights.