What's Your Specific Goal

Before you start training, you need to know what your goal is and the steps you are going to take to acheive that goal. You have to understand the purpose behind every workout, so that you believe in your training. Any doubt and you will not perform your best for both psychological and physiological reasons. If you don't believe the workout will help you accomplish your goal, talk to your coach about it. Either he will show you the purpose behind the workout or he will agree that maybe another workout would better suit your needs on that day in that given training block.
Goals should be both short term and long term. They are accomplished with proper training and consistency. You should not expect the same drop in time from year to year. Rather you should expect yourself to have decreasing drops in time as you continue running. For example your first year of running, a runner might drop his 5k time by 3 minutes, but the second year only drop it by a minute and a half, and the third year only drop it by 30 seconds.
So how should you come up with your goals. First look back at how much training you have completed. Realize that running follows the principle of dimishing returns. Talk to your coach and together come up with a goal.
Lets say that your goal is to run a region qualifying time in the 5k. The qualifying time is 14:10. Your current time is 15:10. First, when do you want to accomplish this goal. In 4 years? 3 years? 2 years? 1 year? Lets say 4 years. Then what should be your goal for each of the next 4 years? Peter Coe, father and coach of one of the greatest middle distance runners in history, Seb Coe, has written that runners follow this formula in coming up with their goals. First figure out how many years you have till you need to run that time. If it is 4 years, add up the numbers 1 through 4: you will get 10. Then figure out your first year's goal by dividing the number of years left to hit the goal/the # 10. Multiply this number .4 by the amount of time you want to drop, 60 seconds and you will get 24 seconds. That is how many seconds you want to drop your time the first year. How about the second year? Well on the second year you have 3 years of training left, so you take 3/10 * 60 seconds and you will want to drop another 18 seconds off your time.
Ex) 15:10 runner wants to run 14:10 at the end of his 4rth year
total time he wants to take off: t=60 seconds
total time he has to train= 4 years
denominator=1+2+3+4=10

1st year

4/10*60=24 seconds to take off
Goal: 14:46
2nd year
3/10*60=18 seconds
Goal:14:28
3rd year
2/10*60=12 sec
Goal: 14:16
4rth year
1/10*60=6 sec
Goal: 14:10

I will give one more example to make sure you understand.

Ex)
14:40 runner wants to run 14:10 at the end of his 3rd year
total time he wants to take off is t=30 seconds
total time he has to train= 3 years
denominator= 1+2+3=6
1st year
3/6*30=15 seconds
Goal: 14:25
2nd year
2/6*30=10 seconds
Goal: 14:15
3rd year
1/6*30=5 seconds
Goal: 14:10

What if you can't run the goal time set out for you on the first year?
This means that your goal may need to be changed. Perhaps you were injured or sick or you didn't train properly. If those are your reasons ,then sure if you get healthy and train correctly then you may still be able to hit your time goals in the next year. BUT if you trained correctly and consistently and you were neither injured or sick then you should change your final time goal to a more realistic time.