HERE is an article with 4 factors you have to consider if you are trying to lose weight and live an overall healthy lifestyle.
Summary:
1) Daily calorie intake (exercise and keep a food journal for at least a week. The results can be pretty eye opening!)
2) Maximum heart rate (use this formula: 208 - 0.7 x Age = maximum heart rate. You should be BELOW this number when you exercise)
3) Target heart rate (50-85% of your maximum heart rate. Just multiply your MHR by 0.5-0.85)
4) Body fat percentage (check out THIS POST for links to calculators for BMI. Women should have a BMI of 18-25)
