I highly recommend cardio exercise as one piece of a weight management program. Here are some tips:
Be sure your cardio workouts are challenging! You should be sweating and breathing moderately hard throughout (unless you have medical conditions–please consult your physician). Your heart rate should be 50-70% of your maximum heart rate (220 minus your age).
Try alternating cardio with strengthening. Maybe do a total of 30 minutes of cardio and 15-20 minutes of weight training, which will boost your metabolism. You can even do cardio intervals of 5-10 minutes with weight intervals for 5-10 minutes. Good, challenging weight training will increase your muscle mass and therefore you will burn more calories throughout the day (not just when exercising).
If you really prefer cardio and not weights, then try changing around the type of cardio you do (spinning, walking, running, aerobics, swimming, hiking, sports, etc). And be sure to increase the intensity or resistance of the cardio as you progress. If it feels too hard, then bump it up and down to your tolerance.