Smartphones have made us too accessible. Everywhere you look, people are glued to their cell phone, oblivious to their surroundings. As a result, some have a hard time disconnecting even at the gym!
I was taking a class recently where a woman had her phone on her for the entire class. What made it worse was the fact that she was using it during class! When the instructor called her out, she had the attitude that this was acceptable. I understand that sometimes we have emergencies, but if you are texting or checking facebook while working out, you are clearly not working hard enough. In addition, this is distracting and disrespectful not only to the instructor but to fellow class participants.
When you are taking time to workout or take a yoga class, it should be stress and distraction free, otherwise what is the point? You owe it to yourself (and your sanity!) to shut it off. Any emails can wait for an hour I say!