Run at a comfortable pace, easy enough that you can hold a conversation. If you're huffing and puffing, you're going too fast. Don't worry about your speed. Just focus on covering the distance.
If you want to add miles, do it on an easy day. Don't extend any run by more than 1 or 2 miles or add miles on Saturday (the day before your long run).
When you're running uphill, don't try to charge up it; you'll spend all your energy by the time you get to the top. Try to run relaxed. Keep your hands loose, and keep your shoulders away from your ears. Just think of letting the road rise to meet you.
The purpose of easy days is to develop the endurance, strength, and cardiovascular fitness you'll need for the race. You don't want to take them so fast that you're sore the next day. At the end of the run, you want to feel like you have the energy to run longer.
Today is your long, slow distance (LSD) run. The long run is the backbone of any successful training program. It builds your aerobic base, increases your endurance, boosts confidence, and helps you rehearse some of the gear and fuel strategies you'll need for the race. It also helps you prepare for the psychological challenge of racing for a few hours. Since you'll be running farther, you can go out slower than you usually do. On these days your goal is just to complete the distance.
In a few days, you'll be doing mile repeats. Next week, you're going to be attempting your first race-pace miles. So it's a good idea to get a sense of what a realistic pace should be for each of those workouts. Just plug a recent race time into the training calculator at runnersworld.com/trainingcalculator.
As your training gets under way, invest in shirts, pants, shorts, underwear, and socks that are made of technical, lightweight fabrics that wick away moisture. These fabrics, such as Dri-FIT and Coolmax, help prevent blisters and chafing.