Been reading through the various posts on running and didn't know to which this should attach, so it's a new one.
My old man is something of a running expert, so I picked his brain about many of the concerns posted on this site.
He distilled the issues down to a few, I'll do my best to relay his thoughts.
Focus will primarily be on durability and injury avoidance.
His background:
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Has run competitively off-and-on for over 50 years.
Coached track (among other sports) for 26 years.
Had various accomplishments in his younger years, too many to catalog here.
At the age of 50, he began competing in USATF age-graded events.
He had many national championships from the 1500m to the half-marathon.
His best 50 year-old 1500m was 4:14 (this is about equivalent to a 4:34 mile).
His best 50 year-old half-marathon was 1:10:44 (this is about 5:40/mile pace).
Named USATF athlete of the year twice in the 50-54 category and once in the 55-59 category.
Has accumulated 19 national championships (including 2 so far this year in the 65-69 category).
At the age of 60, his doc said he had the knees and hips of a 25 year old.
Now, at the age of 65 and weighing in the low 170lb range, he has a resting heart rate of 40 bpm.
He knows his stuff.
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Some of his thoughts:
-Choose your running surface wisely.
Dirt is best, then grass.
Never run on concrete, limit running on asphalt.
All-weather tracks are easy on the joints, but their use should be limited.
They are too smooth. The lower leg benefits from slight surface irregularities.
Overuse of smooth surfaces often causes injury.
-Use
running shoes which are comfortable.
Not racing shoes, not cross-training shoes, or some other "latest" thing.
When they become uncomfortable, replace them.
Don't run in worn-out shoes.
-Warm up slowly. Very slowly.
-Stretch after running. Don't stretch before running.
-Avoid running downhill whenever possible.
Running uphill is a somewhat safe way to keep training while nursing an injury.
(This assumes you have a way to skip the downhill portion.)
-Don't do plyometrics.
They are specialized exercises with narrow (albeit, good) benefits and a
very high risk of injury.
-Don't do "ballistic" stretching.
-Keep your body weight down. Don't weigh more than is necessary.
-Mindset
There are no "magic" pills or techniques.
More is not better. Better is better.
It takes as long as it takes. You cannot get in shape at the last minute.
The will to win is meaningless without the will to prepare.
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Concerning training for PT standards (2 mile):
If the 2 mile is not the primary training goal in your profession or hobby, then keep it simple.
Start training about 8 weeks prior to event testing (perhaps more if you're out of shape).
Run 5 days/week, with rest days being non-consecutive.
Ramp up mileage until you are running 5 miles/day, 5 days/week.
Running 5 miles/day for 5 days/week should be maintained for the 4-5 weeks prior to event testing.
Stop training 2-3 days prior to event testing.
Don't worry about special breathing or running techniques.
Just run.
Your body will learn how to become more efficient all by itself.
HTH, YMMV

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Would be happy to relay specific questions to the old man.
However, realize that individual questions are sometimes difficult to answer because of lack of context.