Sit or lie down and rest
Take slow, deep breaths
Avoid caffeine
Avoid nicotine
Avoid alcohol
Drink water
Cool down if overheated
Reduce stress
Try meditation
Do light, gentle breathing exercises
Avoid strenuous activity
Sleep enough
Eat regular meals
Limit energy drinks
Check for fever
Review medications with a doctor
Seek medical help if the fast heartbeat is severe, persistent, or with chest pain, shortness of breath, dizziness, or fainting