Hello I was wondering how often each week are we suppossed to get our heart rate into our target exercise heart rate zone? I know my exercise heart rate zone is between 137 and 166 beats a minute. Are we basically suppossed to get into this zone every day of the week, most of the days of the week, or only two to three days a week? Oh one more thing, are we suppossed to just stay within our target heart rate zone during exercise or can we go to per se or are we suppossed to get within 75 or 85 percent of our maximum heart rate? If that's the case then I would have to get my heart rate up in the 180s to 190s! Would that be healthy? Anyway thanks for your time and replies. Take care.