At an author’s retreat a few years ago Liz Curtis Higgs grabbed several of us and said, “Come on, let’s take a picture of the Silver Foxes together.” In today's culture that worships youth, her proud ownership of her silvering hair infected all of us. I've never thought of mine quite the same. While ageing is a fact, our attitude determines how we experience it.  And more and more of us are experiencing it.   Experiencecorps.org reports that by 2030 the number of Americans age 55 and older will reach 107.6 million (31 percent of the population). Americans reaching age 65 today have an average life expectancy of an additional…