Stock photography, photos: A couple trail running in winter Stock photos of A couple running in the Sierra mountains in winter. Photograph: © William Stevenson Click for a larger image and more information Keywords associated with this stock photo: Running, runner, run, training, back country, action, active, effort, energy, liveliness, speed, determination, momentum, motivation, strength, aerobic, desire, adventure, freedom, man, male, woman, female, winter, snow, mountains, California, horizontal, distance, vista, vastness, Outdoor, outdoors, outside, sports, sporting, sport, exercise, physical, fitness, outdoorsman, sportsman, adult, young, adventure, adventuring, twenties, 20, s, 30, thirties, 2, two, people, snowy, cold