You should have tempo runs in any training schedule you intend doing. This form of training conditions the body to run faster for longer periods.
This is necessary if you are going for a personal best and have to race at a specific pace to get there.
If you need to run at lets say 5 minutes per kay to get a personal best, then your tempo pace should be just faster than that.
Typical tempo training would go something like this;
Warm up with a slow jog for ten to fifteen minutes.
Decide on what pace your run is going to be at. be realistic, you are not going to be able to sprint for 20 minutes at a time for example, so set yourself a relatively easy target to start with.
Do not make your tempo pace flat out or you will never be able to keep it up, run at a pace just faster than what your race pace will be.
So for example you may run 5 x 800m at tempo pace with 3 minutes recovery in between. Don’t push yourself to hard, if you start feeling very tired, slow down. As the saying goes, Rome wasn’t built in a day.
Don’t forget to warm down afterward. Very important, after a workout like this where your muscles have worked hard it’s essential to warm down.
And as usual, enjoy your running first and foremost. Whats the point if you don’t.
Here’s a video that explains it quite clearly as well.