Not Yet a Runner is general fitness coaching, not medical advice. If you have a heart condition, chest pain, dizziness, uncontrolled blood pressure, are pregnant or recently post-partum, or you are unsure for any reason, get cleared by a doctor before you start. Stop and seek help for chest pain, severe breathlessness or dizziness. Sharp joint pain means stop for the day — soreness that eases as you warm up is normal.