When exercising/working out it is extremely important to warm up and cool down. To prevent injury I extremely recommend reading the documents I have found for you thoroughly, I do not want you to get injured!
http://www.netfit.co.uk/stretching.htm - WARM UP
http://www.netfit.co.uk/stretching_cool_down.htm - COOL DOWN

Week 1-2
For the first two weeks you are going to run 2-3 miles every other day. This might not seem allot but we are going to gradually increase this week by week.

Week 2-3
We are now going to increase our mileage to 4 miles every other day, now by week 2 you could be fatigued. If this is the case you need to push yourself through the tiredness and the pain. It will get better as the weeks progress and as you get fitter.

Week 4-5
We are now going to increase our mileage to 5 miles every other day. Make sure you run this at a steady pace. Don't push yourself too hard, you should be able to run this five miles and not feel exhausted afterwords.

Week 5-6
We are now going to run 6 miles every other day - again keep a steady pace. You should notice that this is becoming quite easy and not too tiring.

Advanced
This is the section where I am currently. You are going to run six miles every other day and 2 miles the days in between that.
This is going to be 24 miles per week.

This is a general upper body work out routine that I follow myself, it's helped me allot and will give you good definition and a muscular upper body.

We are going to do this routine every other day and then every day after a month or so.

• Press-Ups 11 down to 1 TWICE a day.
  
• Sit-Ups 13 down to 1 TWICE a day.
  
• Pull-Ups your limit - ONCE per day.
  
• Plank (both sides as well) 45 seconds each ONCE per day.
  

To really push yourself do all this before a cardiovascular work out. This will really improve your fitness.

It's really important to not strain yourself too much. Only do what your capable of and progress from there. Anything is better than nothing!

When exercising seriously it's important to eat correctly. If you do not supply your body with the nutrients and energy it needs to follow your training programme, your performance will not improve.

It's vital you eat a balanced diet, you should eat plenty of fruit and vegetables along with carbohydrates such as potatoes or pasta, then lean meat or other protein sources.

If you eat a balanced diet then you will not need to take vitamin supplements and you will not need to go on a diet to loose weight because exercise will burn it off.

I'm going to recommend an hour or just under of exercise per day, this is because of your age and the time limitations.
I'm going to start you of on running as your cardiovascular work. I will say you should do a 35 minute paced jog everyday. But before you jog I want you to do 12-1 press-ups and 10-1 sit-ups in the morning and the evening.

Do this for two weeks then we will move you onto phase 2

Please view this thread for stretch tips, eating and hydration.