Pace - with a plea for help...

There is no wall if you pace yourself correctly. - Hal Higdon

I know this. I believe this. I have lived this. However, I continue to make the mistake of shooting out of the gate too quickly. And I always, always pay the price at some point during my run. In my most recent 1/2 marathon I shot out faster than I ever should have. Running my fastest mile up to that point - an 8:15 - and that was mile 1. I usually run around an 8:45 in a pace and a 9:00/9:15 in a regular run. 8:15 should never have been in the cards. It caught up to me and I hit a wall, big time, at mile 10. Almost didn't recover from that.

Fast forward to today. I had a 14-mile run, which sounds short after last week's 19. Well, I shouldn't have let my brain think "short" because 14 is still longer than the longest race I have run to date. I started out fast - too fast. Despite running partners telling me to slow down, five of my first six miles were faster than they should have been. But I did okay...until mile 10. My legs felt like lead. I could barely move them. I wasn't hurting, they just felt tired. I was sluggish. I trudged on, barely for the next three miles. I even had to walk for a bit (maybe a 1/4 mile?). I regained my strength for the last two, but they weren't easy. Here are my splits....

Mile 1: 9:53

Mile 2: 9:44

Mile 3: 10:07

Mile 4: 9:41

Mile 5: 10:28

Mile 6: 9:11 - that just doesn't belong in a long run

Mile 7: 10:01

Mile 8: 10:25 - right around where I should be...maybe 10 seconds faster

Mile 9: 9:50

Mile 10: 10:04

Mile 11: 10:07

Mile 12: 11:44 - and neither does that!!!!

Mile 13: 11:07

Mile 14: 10:38

This was just a practice run. This is where the learning should happen. Not on race day. So I'm trying not to beat myself up...although I have a tendency to do that over even practice runs.

I have a 20-miler on Saturday - my longest race so far. Me, my friend and her hubbie are running together. We are treating it like a long run - not a race. We don't want to run it at race pace. Especially since there is about a minute difference between their race pace and mine.

So, here's the question (and please, please comment - I need tips)....How do you stop yourself from shooting out too quickly in the beginning? I cannot afford to do that come marathon time, but if I don't learn it now, it could be a tough lesson to learn that day. Any tips? Anything you've tried that worked? I would love any advice. I didn't plan on wearing a watch on marathon day (it's my first and I don't want time to be a factor), but wondering if I should just to make sure I'm not starting out too fast. Any thoughts would be appreciated.