Whenever I go to the gym I always check my heart rate periodically throughout my workout (and some times at dance I count it when I remember). Even though I have a fairly active lifestyle my heart rate has always been high when active and low when inactive. For example today my heart rate at the end of my cardio was 193 beats/min, and was between 183-195 throughout. When I look at the scale things at the gym or when I use an online calculator it says I should be more around 140-160. What does this mean exactly? What can I do to lower my heart rate (if necessary)?

Heart rate monitors on moving machines (like a treadmill or elliptical) are incredibly inaccurate and may as well be disregarded. If you are using a real heart rate monitor- like a Garmin chest strap- that is far more accurate. Increasing your cardiovascular fitness tends to lower ones heart rate; resting and active. By cardio, I mean non-stop movement like running, jogging, cycling, etc. Dance doesn't really count because it is 'stop and go'.

Is there any reason you are really concerned with your heart rate? Go to the doctor if you are alarmed or have chest pain.