This is an app that I love. If you feel that your heart is racing at any time, you can use this app to measure your heart rate! It can sometimes be difficult for people to find their pulse, but this app does the job for you!
For adults 18 years of age or older, a heart rate of 60-100 beats per minute (bpm) is considered normal. Well-conditioned athletes can have slower heart rates from 40-60 bpm. Heart rates will rise with exercise. To figure out your maximum heart rate, subtract your age from 220. For instance, if you are 40 years old, your maximum heart rate would be 180 bpm. When you exercise, you can measure your heart rate, and you should aim for a heart rate between 50-85% of your maximum heart rate. More vigorous exercise will increase the heart rate.
Enjoy this free app! It is available for iOS and Android.