Get in the Zone for proper exercise intensity

Finding the right intensity to exercise at is important to maximize the safety and effectiveness of your workout.
One of the best ways to monitor the intensity of your workout is with your heart rate. Find the appropriate “zone” for your exercise to meet your goals, try to keep your heart rate during the workout in this zone. Consult your physician if you have any risk factors for cardiovascular problems or if you are unsure if you might have some. Next calculate your submax heart rate; your physician can help you with this if you have any risk factors. If not, then this can be found by walking or running at a sustainable pace at near maximum effort for 15-20 minutes after warming up and then check your heart rate at the end. This is your submax heart rate.
Healthy Heart Zone (Warm up 60-70% submax rate) --- The easiest zone and probably the best zone for people just starting a fitness program. It can also be used as a warm up for more serious exercisers. This zone has been shown to help decrease body fat, blood pressure and cholesterol. It also decreases the risk of degenerative diseases and has a low risk of injury.
Fitness Zone (Fat Burning 70-80% submax rate) --- This zone provides the same benefits as the healthy heart zone, but is more intense and burns more total calories.
Aerobic Zone (Endurance Training 80-90% submax rate) --- The aerobic zone will improve your cardiovascular and respiratory system AND increase the size and strength of your heart. This is the best zone to progress toward with your exercise program for long term health benefits.
Anaerobic Zone (Performance Training 90-100% submax rate) --- Benefits of this zone include an improved VO2 maximum (the highest amount of oxygen one can consume during exercise) and thus an improved cardiorespiratory system, and a higher lactate tolerance ability which means your endurance will improve and you'll be able to fight fatigue better. If you are training for a competition of some sort you need to get into this zone to improve your performance.
High Intensity Interval Training (Maximum Effort 100-110% submax rate) --- Although this zone burns the highest number of calories, it is very intense. Most people can only stay in this zone for short periods. You should only train in this zone if you are in very good shape and have been cleared by a physician to do so. Implementing short bursts (1-2 minutes, 5-6 times) of this intensity with easy rest periods in between can have significant health and fat burning effects, but care needs to be taken.