I was only 15 minutes into my 10-mile workout when the cold metal wrapped around my neck made me regret my latest attempt at long-run entertainment. I was fighting a losing battle against boredom, and you know what they say about desperate times. This didn’t used to be a problem. Before starting at Runner’s World , I focused on shorter distances and never had to run continuously for more than 30, maybe 45 minutes at a time. But after I joined the staff, inspired by my coworkers, my long runs ballooned to hours in length, requiring new tactics. I’ve spent the past year or so experimenting with different ways to pass the time , with varying degrees of success. Here’s how they measured up: Mental Exercises Inspired by the trend of “rawdogging” flights (where passengers do nothing but stare at the seat in front of them for the duration of the trip), there were a couple of long runs where I set out with nothing but my thoughts.…