A fast heartbeat when thinking about the past or future is often due to anxiety or stress triggering your body?s response, even if your blood pressure is normal. Try simple calming methods like slow deep breathing or grounding yourself in the present moment when it starts, and keep a routine with proper sleep and light daily activity to stabilise your body. Reducing tea, coffee, and long screen time can also help, and sharing your thoughts with someone you trust may ease the mental load. Practising short relaxation or mindfulness exercises daily can make these episodes less frequent. If episodes become more intense, more frequent, or accompanied by dizziness or chest discomfort, consult a doctor to assess and guide you in managing them effectively.