Play Beat the ClockI love doing this when I'm running an out-and-back route. Begin timing your run as soon as you start. At your turnaround point, hit the split button on your running watch/timer, or just take note of your time. Try increasing your pace on the way back, with the goal of beating your time for the first half (which, by the way, is called a negative split).
Do a Random Interval WorkoutPick a landmark in the distance, such as a tree or a stop sign, and pick up the pace until you get to it. After you recover for a minute or two, choose another landmark and speed up again.
Do Some Hill RepeatsPlan a route that has at least one hill in it and, when you come to it, run up and down it a few times before moving on.
More: How to Run Hills
Hill Treadmill Workout
Benefits of Hill Running
Get a Running BuddyDo you usually run alone? Try to convince a friend or family member to come along with you -- even if it's just once a week. Even if they're slower than you, you'll find that helping someone else will help get you excited about running again. If you can't find anyone who will run with you, follow these tips to find a running group.
Also see: Tips for Being a Friendly Runner
Count 'Em UpIf you run where there are a lot of other runners, try this game: Pick out a specific article of clothing, such as black running shorts, to look for during your run. Then count how many runners you see wearing that piece of clothing. If you're running with a friend, you can each guess how many you'll spot during the run and then see who comes the closest.
Also see: 10 Things Runners Should Stop Doing