Well, if Army or for that matter, forces were to mean only physical prowess, many men that you see in there, would have never made it. But all of the officers have one thing in common, leadership traits and by that I mean, a strong will and determination in reference to your question. Human body is capable of sustaining much more than what you and me think. It is mind which makes you think you are strong or weak. So once you qualify SSB, you will go through training academy and it will slowly build your stamina. You won't run 5 kilometers with backpack and weapon in a single day. But you will be successful ultimately, not because you are weak or strong physically but you will control your mind and make sure you go on when you feel like stopping.
After your commissioning, you will have much more to do than physical regimen and your real strength comes out when you are sitting in the office and you will have to take a tough decision to ensure that you motivate your troops to transfer ammunition in below zero degrees.
Or you might have to deal with an unruly crowd which is out to damage your posts and you have to take a decision to fire at them or wait for civil police to arrive. That is where your real strength lies. And that is where military will ask you, 'Do you have it in you'?
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