The heartbeat of people who basically don't exercise is between 70- 100, that of people who like sports is between 50- 100, and that of long-term fitness or athletes is between 40- 100 (even as high as 35 when sleeping). That's because their hearts are very thick and strong, and every beat can perfectly input oxygen to every part of the body. When the heartbeat is slow, you don't feel pain before and after the left chest, or it doesn't matter if you have mild angina! If you have these symptoms, please go to the hospital in time. Be sure not to be afraid and keep a healthy mood.