There are 3 categories of exercises: cardiovascular, strength-building, and flexibility.
Cardiovascular exercise is also known as aerobic exercise. Aerobic exercise uses your large muscles and can be continued for long periods. For example, walking, jogging, swimming, and cycling are aerobic activities. These types of exercises drive your body to use oxygen more efficiently and deliver maximum benefits to your heart, lungs, and circulatory system.
Strength-building and flexibility exercises are known as anaerobic exercise. Anaerobic exercise does not have cardiovascular benefits, but it makes your muscles and bones stronger. Strength-building exercises require short, intense effort. Flexibility exercises, which are also anaerobic, tone your muscles through stretching and can prevent muscle and joint problems later in life.
A simple definition of cardiovascular exercise is any exercise that raises your heart rate to a level where you can still talk, but you start to sweat a little. 20 or more minutes of a cardiovascular exercise 3x week is usually needed to get cardiovascular benefits.
There are certain types of blood pressure medicines that will lower the heart rate also. I took one which lowered my heart rate to in the 40s

But mine is normally in high 50s /low 60s on average anyway..
Other interesting facts
Fish lowers heart rate --
http://www.thestressoflife.com/fish_lowers_heart_rate.htm
There are herbal medicines you could take but I would not suggest it without talking to herbalist or doctor. They could be dangerous.