Anyone that hasn't exercised must start out at a small pace. First you need to warm up before doing anything. Jumping into an exercise just puts a strain on the heart all of a sudden. You want to start out slow, then slowly work your pace up for awhile then walk at one pace for 10-15 minutes and then cool down before stopping. Do this for several days and then slowly work yourself up to a faster pace into a slow jog if you want. You are also right about going to your doctor before starting any exercise routine, even walking. After his okay just remember to warm up and cool down when exercising. This way your muscles won't cramp and remember your heart is the largest muscle we have. Good luck with your exercising and God Bless