To counteract the midday gloom, consider a brief yoga break. (Theodore Tae/The New York Times) By CHRISTINE YU For many people, the afternoon is a dreaded time of day when energy slumps, concentration fizzles and stress builds. To counteract the midday gloom, consider a brief yoga break. It’s a great way to pause and reset your body and mind, said Elena Cheung, a yoga instructor and yoga teacher trainer in Seattle. Yoga can also help offset the effects of prolonged sitting, said Christiane...