I had an icd implanted 2mos.ago and starting to exercise again.I am cautious about this since I am not sure how much to do. I use my treadmill for 1hr.each time and been keeping it slow about 1mi.I want to increase it to a faster pace,but not sure how gradual it should be.My ef is 18 so I am wondering if I will cause a problem with my icd.