Every two weeks increase your distance by 2 miles. Focus on strength training 3 times a week and increase intensity at each work-out until you are at a plateau. Continue there building endurance. Keep a record of your heart rate so you don't overdo it.
Answer:
It's gym
Explanation:
You'll have to do the workout.
Its a symptom of any number of things; Pericardial Tamponades (fluid buildup of sac surrounding heart), a heart contusion, a dysrhytmia like Ventricular Fibrillation or Ventricular Tachycardia...