1. Find your resting heart rate-
To do this take your pulse for ten seconds as soon as you wake up. Then multiply that number by six.
You now have your resting heart rate. To ensure accuracy do this for several days and then find the average.
(Many things can effect your daily heart rate such as stress, dreams, what you ate the day before etc.)
example -
Day one. 68 beats per minute, Day two. 74 beats per minute
Resting Heart Rate = 71

2. Discovering your maximum heart rate-
Subtract your age from 220.
example -
If you are 35 years old, 220-35=185
Your Max Heart Rate is 185 beats per minute.

3. Calculate you Heart Rate Reserve-
Subtract your resting heart rate from your maximum heart rate
example -
So if your resting heart rate is 71 and you are 35 years old your heart rate reserve is 114

4. Your target heart rate-
Multiply your heart rate reserve by .7 and then add your resting heart rate to that number.
example -
114*.7=79.8 (round up to 80), 80+71=151
So your target heart rate is 151 beats per minute.