The problem with the military is those are the only two exercises they employ. Push ups and sit-ups. It doesn't matter how strong you are, or how many other exercises you can do to failure. They only care about those two. You also have to worry about chin-ups if you're going into the Marines or Army, but no other branch employs chin-ups.
I wouldn't worry much about training for those things unless you just totally want to blow **** out of the water when you get there. I remember when I got into the military, I couldn't do 2 push-ups, but after boot camp was over I was able to do somewhere around 70 in two minutes (funny how that works. I could go from my back into a handstand, but not do a push-up...wtf). Ask me to do 70 push-ups now and I couldn't come close, lol. And I have much more upper body strength now, than I did back then.
Your body will get conditioned to those exercises. It doesn't matter what kind of core strength you have, doing sit-ups will be your only prep for doing the amount of sit-ups with ease that they will want you to be doing. I had pretty good core strength before I joined the military from break dancing...it only HELPED with the sit-ups, but it didn't do much else. Doing sit-ups helped my sit-ups. FWIW, I was able to do 98ish (can't remember, but remember it was just shy of 100) situps in two minutes. I have no idea what I could do now, and I have more core strength now than I did.
But onto the topic of running, lol. 14 minutes is a good 2 mile time. Running sucks. I've never met anybody that truly enjoyed running. Yes, everybody loves the sense of accomplishment afterwards, but you never hear anybody go "that was really a good run today", like you hear from cyclists. Well, at least I've never heard anybody say that, and I used to run pretty avidly with some pretty gnarly runners.
Its normal. Great time, and good job! What is your goal?