There are MANY exercises that you can do at home with minimal equipment or time commitment that will strengthen and enhance your training and allow you to be at your best when you do your race.
Here are a few exercises that can be done at home to work on starting to strengthen your key "running" muscles;
1) Wall sit- lean you back again a wall and bring your feet out from the wall so that when you slide down the wall till your thighs are parallel with the floor, your knees are directly over your feet. You do not want your feet too close into the wall so your knees push forward past them. Hold the position for 30-60sec. if you feel any sort of ache or pain in the knees, squeezing a volleyball size ball between your knees will trigger the VMO muscles on the inside of the knee and most of the time it takes away most pain.
2) Clamshells- Lying on your side, keep knees bent and feet together (see pic). Keep hips stationary then open up knees and repeat. 15x