If you are a self-confessed couch potato and would like to inject running in your lifestyle, it may be difficult at first, but very doable. Usually, your friends may have been going to a gym, like the Bally Total Fitness, Goodlife Fitness, or Retro Fitness then they were told to try half marathon training. Of course it is fun to do it with friends, because friends are a good support system to let you continue with the goal. You may also try going with them to the Bally Total Fitness so that you will meet more friends who are enthusiastic about the idea.
If you try to run initially without training, you may find yourself in big trouble. Since you have been living a sedentary life for quite some time, going back to shape is a sure shot to help you finish that half marathon. You may also enlist the help of the pros to guide you on road to success.
Start From the Beginning
So, basically you will start from zero. That may seem harsh but it is better to accept that fact from the start. To at least accept whatever the difficulty you may experience during the course of the training. The only thing that will fuel you up to excel at this is your determination.
With this in mind, set yourself for training for 14 weeks. Yes, you will train for more than 3 months. So you might bargain, that you were running before, and that you just stopped because of work or family matters. The concept here is to train again, so let us start from the basic and lighter exercises, working your way up. If you skip this and start midway, chances are you will be dissuaded.
Plan a Schedule
You must plan a schedule that requires no more than 4 days of running per week. It would be better to make a chart, post it on the wall in your bedroom or bathroom or even on the door of your refrigerator. Highlight the days you are not running and write there “OFF” so that it will remind you to rest those days. Do not take rest lightly as they are 
needed by the body to maintain good health.
Reminder
Always do warm-up exercises and cooling down exercises. Warm-up by stretching your muscles to prepare them for the task ahead. Cool down to let the muscles relax.
Now, Let us Keep Moving!
This is a 14-Week Plan as suggested by Experts from Women Running:
14-WEEK PLAN
Week 1:
Monday: OFF
Tuesday: R/W 2 miles
Wednesday: XT 30 min
Thursday: R/W 2 miles
Friday: OFF
Saturday: R/W 3 miles
Sunday: W 2 miles
Week 2:
Monday: OFF
Tuesday: R/W 3 miles + ST
Wednesday: XT 30 min
Thursday: R/W 2 miles
Friday: OFF
Saturday: R/W 3 miles
Sunday: W 2 miles
Week 3:
Monday: OFF
Tuesday: R/W 3 miles + ST
Wednesday: XT 30 min
Thursday: R/W 2 miles
Friday: OFF
Saturday: R/W 3 miles
Sunday: W 2 miles
Week 4:
Monday: OFF
Tuesday: ER 2 miles + ST
Wednesday: XT 30 min
Thursday: ER 3 miles
Friday: OFF
Saturday: ER 4 miles
Sunday: W 3 miles
Week 5:
Monday: OFF
Tuesday: ER 3 miles + ST
Wednesday: XT 40 min
Thursday: ER 3 miles
Friday: OFF
Saturday: ER 5 miles
Sunday: R/W 3 miles
Week 6:
Monday: OFF
Tuesday: ER 3 miles + ST
Wednesday: XT 40 min
Thursday: ER 3 miles
Friday: OFF
Saturday: ER 6 miles
Sunday: R/W 3 miles
Week 7:
Monday: OFF
Tuesday: ER 4 miles + ST
Wednesday: XT 40 min
Thursday: ER 4 miles
Friday: OFF
Saturday: ER 7 miles
Sunday: R/W 3 miles
Week 8:
Monday: OFF
Tuesday: ER 4 miles + ST
Wednesday: XT 40 min
Thursday: TR 4 miles
Friday: OFF
Saturday: ER 8 miles
Sunday: R/W 3 miles
Week 9:
Monday: OFF
Tuesday: ER 4 miles + ST
Wednesday: XT 45 min
Thursday: TR 4 miles
Friday: XT 30 min or OFF
Saturday: ER 9 miles
Sunday: R/W 4 miles
Week 10:
Monday: OFF
Tuesday: ER 4 miles + ST
Wednesday: XT 40 min
Thursday: TR 4 miles
Friday: XT 30 min or OFF
Saturday: ER 10 miles
Sunday: R/W 3 miles
Week 11:
Monday: OFF
Tuesday: ER 4 miles + ST
Wednesday: XT 40 min
Thursday: TR 4 miles
Friday: XT 30 min or OFF
Saturday: ER 10 miles
Sunday: R/W 3 miles
Week 12:
Monday: Rest
Tuesday: ER 4 miles + ST
Wednesday: XT 40 minutes
Thursday: TR 4 miles
Friday: Rest
Saturday: ER 11 miles
Sunday: R/W 3 miles
Week 13:
Monday: OFF
Tuesday: ER 4 miles + ST
Wednesday: XT 40 minutes
Thursday: ER 4 miles
Friday: OFF
Saturday: ER 6 miles
Sunday: R/W 3 miles
Week 14:
Monday: OFF
Tuesday: ER 4 miles
Wednesday: Rest
Thursday: ER 3 miles
Friday: OFF
Saturday: ER 2 miles
Sunday: Half marathon!
Legend:
W = Walk at a brisk pace
ER = Run at an easy, conversational pace
R/W = Easy run with walk intervals
TR = Tempo run
XT= Cross train
ST= Strength train
OFF=Rest days
So, good luck and in 14 weeks, you are ready!