EXERCISE WITH A COLD? Three days after my return from visiting my son and his family in Florida I came down with a cold.  (The risks of air travel and long hours in airports, surrounded by countless people, caught up with me.) This cold persisted for three full weeks, but as of today, my runny nose and coughing have finally ceased. Before my trip, I was training for a 10K running competition, which was scheduled for last Sunday. However, when I went jogging a couple of days into my cold, I could barely finish 4K without feeling exhausted.  So I...