Lol @ many things said in thread.
You’re legally required to do this. It won’t change, and if you dwell on it you’re just going to make yourself suffer.
I understand you may be overwhelmed and stressed but that is literally the easiest physical I have ever heard of, nevermind for military application. You could not imagine what some units have to face. You best pray you never face a war then my friend! Given the geopolitics right now, well…
Anyways, recommendations, as Churchill said, if you’re going through hell, keep going. “Tough” things will only make you tougher. It’s pretty short time and later you will have some cool stories.
Since pushups seem your biggest issue, try to do as many pushups as you can each day a couple tries, it will get you to 30 in less than 2 minutes pretty fast. Maybe first when you wake up. If you get stressed or upset, that is a great time to try some, it will help both angles. Listen to music that motivates you if possible. Trust me. Don’t dip too far down if you are bad when the time comes for test and find out how spread out yours arms is best for you makes it easier. Same deal with pullups (you only have to do ONE?!
), and going faster is usually easier if your strength is low as slow just pushes the muscles harder. 3km is nothing, just jog, keep hands up above elbows and like loose fist and try breathe more through your nose, don’t overdrink water and think positive. Keep your head up.
Take some multi-vitamins if you are vegetarian, your diet might be letting you down more. This will help lots if possible.
More advanced, for guns just remember a couple solid rules… Always imagine every gun is loaded, even if you think or know they’re not, like point downward as much as you can and never toward anybody or anything. Keep your finger off the trigger until actually time to shoot and when you lift gun always keep pointed toward where it’s safe to shoot, don’t turn around toward anywhere unsafe when up like a person. Always clear the weapon before and after, even if someone tells you it’s clear or you even watched them clear it, if you handle the gun make sure you remove the magazine and clear/check chamber more than once. Not sure which gun ROC uses to train but Google is your friend since you clearly have internet access. Good aim is usually not a requirement lol Grenades won’t magically explode so don’t be afraid, just follow directions, and throw confidently outward and up and then get down. Again, ask people then Google specific type and learn how the pin/lever mechanism works in advance if you are nervous. Since it’s training, likely not real so literally not a thing to fear. Practice throwing like it’s baseball because i’ve seen people toss like 7 year old girls before and it’s the embarassment that will hurt more than anything else 
Short of it, don’t be a weak sounding coward bro, that’ dumb. Enjoy where you can, learn all you can and make friends. Be glad you are just training and that’s all. Peace be with you.