I would fare terribly in real life war. I am not fit, I have poor reaction times, I cannot run fast and I would almost certainly would not be able to fit in with a squad of "tough fightin' men", given that I am introverted, silent and opinionated. If my squad-mates didn't shoot me in the back to shut me up (and that happens a surprising amount in war), then the enemy would probably shoot my wobbly, slow moving, weak body with bullets.
That is, of course, if I was in the infantry on the front lines. Most soldiers, believe it or not, NEVER see combat. EVER. That doesn't mean they have it easy - they are still in danger, and they have to work very hard, but a fair number of soldiers don't actually fight, but instead handle paper work, logistics, repairs and military police work. For every 1 soldier on the front lines, there's at least 5 who are responsible for supplying, organizing and sending that soldier there.
So if I was in the army, I think that my terrible physique, lack of co-ordination and general unsociability would help land me either a desk job, a medical job (I have training in biological sciences) or a suicidally dangerous job. Hey, I've read a lot of military history books - it is NOT uncommon for an officer to give a hated member of his squad a dangerous job in the hopes of getting him killed. And it is also not uncommon for hated officers to suddenly get "killed in action" by a bullet to the head while he's sleeping. You know it happens. It isn't all sunshine and roses in the military - either you fit in, and you do well, or you don't fit in and it's really awful. I know that I would NOT get along with fellow members of the army. I talk too little, I don't open up, I don't trust people and I am highly, HIGHLY opinionated - none of which would endear me to others.