Running Tip #2. "Pace yourself" is easy to say but difficult to do! Set a realistic goal pace based on training, and start at least 5 seconds / mile slower. Force yourself to check your pace despite adrenaline and ability to run faster. Ease in to your goal pace after the first 10k, control through the next 20k, knowing you can pick it up the last 10k and finish strong.
I have learned to improve pacing both by trial and error as well as volunteering as a coach, guide, and pacer with Achilles International, where I have helped pace several of my athletes to beat their goal times at the NYC Marathon.