I have a very high heart rate while exercising and a very low heart rate while resting. Is this normal or do I need to see a doctor?

Physical fitness? Well conditioned athletes often have low heart rates at rest (sometimes 40 - 50 bpm). Your maximum heart rate should be 220 - age (i.e. ~171 bpm for a 49 y/o). If your heart rate rises above this, abruptly rises to this rate, or you have dizziness, short breath, or chest pain, see a cardiologist to make sure you're not experiencing an arrhythmia. Otherwise, this range is normal for athletes.