no lah..he's NOT NSmen leh..but NSF....
dun just train for "long" distance, that will only develop stamina,
endurance and strength (if got some slope).
What you need is to develop SPEED!...how?
do interval trainings to vastly increase your
cardio-strength....something like anaerobic..
1). run at near to MAX speed for 400 meters, then jog or walk next
1 to 2 mins, then do again and again...
2) Do. no.1 slowly and later increase to near Max. speed for 600m,
800m, etc.
and including the 1 to 2 min rest time.....
3). by the time you can do that for 1000m, you should have improve
your overall speed (due to lungs accustomisation), and therefore
decreased your timing by at least 1min 30s.
This is assuming when you run, its your lungs that "heat" up first
and not your legs that get tired first. (i.e. assuming ample leg
muscles and back, adominal muscles)
How back and lat-adominal muscles help to maintain or improve
overall running performance?
1). When running, you are in the upright position and slightly
crouged, etc.. so you always see people running 2.4km, cannot tahan
the sides of the stomach and use hands to support them...so u need
to improve this...do some stomach lat-exercises, best u got gym to
do. 
Next, when running, dont anyhow breathe in and out. Do
"synchronised"-breathing...that is either
1). 2 steps breathe in , 2 steps breathe out or 3,3 or 1,1
2). Best is, when you start running 2.4km, u can start with
2,2....then at the last 800m, change to 1,1...i.e. left leg breathe
in, right leg breathe out...
this will give additional oxygen to your lungs and give you more
energy and stamina. But use this as your last power-boost, i.e.
dont use it at too early a stage. else it will "over"-oxygenate
your lungs and "heating" up will occur and that will decrease your
endurance drastically.
Lastly, go borrow books from library about running or visit the
mindef.gov.sg website, where they give you general instructions to
"PASSING" all your stations in IPPT.
CHEERS! 
