Workout alone might not be sufficient to "lose 8 lbs." If your caloric intake is higher that your caloric burn rate, you won't lose any weight. Some folks eat more than before when they start a new exercise routine, so they don't lose any weight although they are exercising more.
In general, a good breakfast, good lunch, and light dinner and aeorbic exercises are a good way to lose weight. For exercising, you need to slowly increase your intensity as you can easliy hurt yourself.