With such a topic so broad we truly try to cover the basics from all angles in this group. Nothing too big or too small. Nutrition is as significant if not more as exercise is to reaching your goals so learn all you can.
What is your baseline calorie amount you have been eating? Have you just lost weight? gained weight?
Look up BMR Basal Metabolic Rate equation and figure it out according to your weight and height, then figure out how many calories you expend doing your daily activities and add that to your BMR calorie amount - that amount should be your maintainance amount.
Other than that I am not sure what you mean.... doing 20-30 minutes 3-5 times a week is good for your heart and body.
-------------- Argue for your limitations, and sure enough, they\'re yours.
Richard Bach