Hello, I'm A 26 Years Old Female, Very Active, Train

Hello, I'm a 26 years old female, very active, train 6 times a week, eat very healthy every 3 hours throughout the day, former smoker (quit 3 years ago), sometimes use E-cigarette (minimal nicotine), drink about 3-4 cups of coffee per day, and my resting heart rate is very high, almost never less then 100 pm, and sometimes as high as 120 pm when resting. What could the cause be, and should I get examined by a doctor?