paid $80 for, told all of your friends your going to do, thought about and trained for months, those are not so hard. It's all the runs in between that are hard.
Last night as I headed out for my run after work my iPod died. It took everything in me not to get in my car and drive home. I was hungry, I was tired, and more importantly the only person who would have noticed that I didn't run was me. But when you start thinking "I can skip this run", then you start thinking you can skip every run. And pretty soon you're sitting on the couch watching back to back Real World episodes until you've seen them all (not that I'm one to get sucked in by really bad reality tv, no, no, not me).
And really I should clarify, once I'm running I love it. It's motivating myself to take that first step that just plain sucks. For me putting my shoes on takes way more effort than a 5 miler. But once I'm out there, listening to the sound of the waves crashing on the beach, in this beautiful place I'm so fortunate to live in it really is easy - I just put one foot in front of the other, and repeat.