Updated December 20, 2014.
Running a half marathon tests your mental strength as much as it does your physical fitness. Each part of the half marathon has different mental battles. Here are some tips on how to win the challenges throughout the half marathon and run a successful race:
First 5 Miles:

Start out slow. When you start your half marathon, you'll feel strong and confident, but you have to tell yourself to hold back.

The first few miles should feel easy -- after all, you've trained to go 13.1 miles. Running your first half slower than the second half (called a negative split) is the key to running a smart and enjoyable half marathon. Take it slow. Your body will thank you during the later miles.

Run your own half marathon. Don't be worried if you see a lot of people passing you. Remember the tortoise and the hare? They may be starting out way too fast, so you'll catch them later -- at your own pace. Going out too fast is one of the most common racing mistakes.

Don't get too emotional. Try to stay as calm as possible for the first 5 miles. Resist the urge to high five spectators and jump up and down when you see family and friends cheering for you. You'll want to conserve your mental energy for the rest of the half marathon.

Miles 6-10:

Break up the half marathon. Start breaking up the race into smaller segments. It will make the distance feel more manageable. At mile 10, for example, think, "It's just a 5K to go."

Stay mentally tough. Your mental toughness will really start to be tested during these miles. Don't give into periods of self-doubt and discomfort. Remember all those miles you ran and the training you did, and have faith in it. Think about how hard you have worked and how rewarding it will be to complete your half marathon.

Beat boredom. Here's when you really get to use all those boredom-battling tricks you tried out during your long runs. Do whatever it takes to keep your mind occupied: Sing songs, play mental games, count people, talk to other runners.

Miles 11-13.1:

Think outside the body. You may feel a little discomfort during these miles. You'll definitely feel tired. Let your mind take over from your body and try to focus on the outside -- the people cheering, the spectator signs, the other runners, the scenery.

Talk to yourself. At this point in the race, you need to dig down deep for extra strength. Use your running mantras that you used during your training runs. Remind yourself what you've sacrificed to get to this point and how you're going to feel when you cross the finish line. Remember how you've worked through fatigue during training and how you can do it again.

Set small milestones. Continue to break up the course, mile by mile. Start counting down the miles and the minutes.

Also see: Tips for Running Your First Half Marathon
13 Things to Know Before Running a Half Marathon
10 Best Things About Running a Half Marathon
6 Commonly-Asked Questions About Half Marathon Running