What trainers actually think about the 12-3-30 workout

What trainers actually think about the 12-3-30 workout

Look at this room full of treadmills — it’s an entire world of 12-3-30s just waiting to be tapped into. | Boston Globe via Getty Images When it comes to exercise, so many people — beginners; die-hard enthusiasts; reluctant participants; and everyone in between — are...