PHOENIX -- About 5,000 people gathered in downtown Phoenix Sunday morning for the 39th Annual Phoenix 10K & Half Marathon.Race proceeds benefit the Mollen Foundation, which is dedicated to preventing childhood obesity.Dr. Art Mollen was at the event and shared some tips for running a big race:1. Pace yourself at the beginning. You should be able to have a normal conversation with the person next to you.2. Remember to stretch, even during the race, to keep from getting an injury.3. Don't wear a new pair of shoes on the day of the race. This can lead to blisters and tendinitis.4. Don't wear heavy clothing that could cause you to overheat.5. Drink water during the race. If you wait until you feel thirsty, you're already dehydrated.6. Don't eat a big meal the morning of the race.7. Strive for your personal best rather than trying to keep up with other runners.