To attain your top potential, you will need to build gradually through the training cycle. The length of the training cycle will depend on your goals. Those running shorter races like the mile, 5k and 10k might consider training cycles of two to four months. Others who would like to be able to race at peak performance for four to eight weeks or want to peak for a single 10K or marathon might consider longer training cycles of four to six months.

Endurance
This phase is the longest and most important in the training cycle. During this time, the heart, lungs and mind are conditioned to run for long periods of time. The objective of this phase of training is to keep the body moving longer, not faster. Namely, you are safely building your mileage up to your planned upper limit.

Strength Training
This phase is where you begin to condition yourself to run faster and stronger. It is when you begin to transition into speedwork. You do this by adding hills to your routine and maybe one or two fartlek and tempo runs. During this phase you may add a weight program and consider running a couple races.

Speedwork
This phase is where you peak. While your mileage will remain high, it will be slightly less than in the endurance and strength phases. Quality runs are more important than quantity now.  The strength workouts are replaced by trackwork.  This completes complete the mix of endurance stamina and speed.

Tapering
This phase is all about resting.  The amount of rest you are going to need will depend on the distance you plan to race.  The longer your race, the more rest you should take. Typically, the taper phase lasts one or two weeks.  Don't stop running entirely but cut your mileage way back.

Racing
You are in peak condition and ready to race. Cut back your mileage, stay sharp during training and go for it.

Recovery
Rest! Rest! Rest! you don't have to stop running entirely, but limit yourself to easy running or cross training. Keep in mind that after this phase, you will return to the beginning and start building your endurance again.