DEAR HARRIETTE: I went to visit my sister, who is single and retired. We talk on the phone a lot, but we haven’t spent time together for a couple of years. I was surprised to see how sedentary her life has become. Basically she sits around and watches TV all day. She looks at romantic movies back-to-back from the time she wakes up until late at night. The only time she looks at anything else is wh…