what kind of training are you doing now, how old are you, and how long have you been running? do you run for your school track team or something like that? the training that jeff mentioned would be good for someone who has at least a good year or two of training under his/ her belt, a lot of experience, and wants a hardcore training regimine to really get the best possible performance that they can out of their body. i have a feeling that something less intense could help you reach your goal with a much smaller chance of injury.
even at a varsity level, training for 5K races, very few runners do 12 mile long runs, or even 10. and if tweetypie's 1.5 mi race pace is 8:20 pace, she obviously shouldnt expect to run 8mi in 60 min like you suggested (7:30 pace).
i love to tell my story about when i started running seriously: in 8th grade my mile time was 7:47 (i probably would have had a 1.5 mile time similar to yours), and i ran jr. high track (i was a sprinter). i got recruited for my high school cross country team, the coach gave us a summer training schedule, and i was hooked. even though i couldnt finish the 2mi scheduled for the first day w/o walking, i kept at it, and by the last day i could run 6mi at 8:15 pace. once the season started...the freshman cross country course was 1.5 mi, and i was under 10:00 (under 6:40 pace) by my second time racing it, with only a month or so training with the team.
the schedule my coach gave us was simple and its goal was to build our endurance. its a simpler, less intense version of the aerobic stage jeff mentioned, and it went like this:
week 1: 2mi every day
week 2: 3mi every day except saturday off
week 3: 3mi every day
week 4: 4mi every day except saturday off
week 5: 4mi every day
week 6: 4mi every day except saturday off
week 7: 5 mi every day except 6 on saturday
like i said, simple. but it got me in shape, and quick. if i had never run it and saw someone post it now, i would probably criticize it...theres no tempo runs, no intervals, no fartleks, no hills, no ANYTHING...plus there's not much of an opportunity for rest for a new runner which invites injury. theres not much variety, either, which invites boredom...and that may be worse than injury when it comes to hooking a new runner on the sport.
but it WORKED.
this is all assuming that youre not training much now, and you havent developed your endurance. if 2mi is nothing for you, start with three. start with four. if your goal race is in 3months, you might want to cut the base-building to 5 weeks instead of 7. then do 3 weeks of strength-buidling (this is where you start specializing: tempo runs, fartleks, long runs, and hills, with easy days in-between hard workouts); 3 weeks of speed (anaerobic), similar to strength but less distance and more speed, and throw in some interval workouts too; and a week to taper. if you have a bunch of races and not just one goal one, you may need to change this schedule a bit since youll need an easy day before and after each race, but you wont need the weeklong taper.
i could be completely off-track here...i could help more if you told me, like i said: what kind of training are you doing now, how old are you, and how long have you been running?
(and jeff, i hope you dont feel so bad about "flooding" this thread now, since ive said twice as much as you, and in a single post.

this could very well be the longest post ive ever posted, and i have a history of lengthy posts.)
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