Arpan, most large aircraft are not stressed to take excessive accelerations ('G'). No airliner I know is certificated to 3G; 2.5G or less is the normal structural limit, with -0G being the negative limit. No passenger would ever thank us for exploring these limits! They're there to allow for the stresses of extreme turbulence, not for daily use.
I don't know whether you've ever flown on an airliner, but if you have you should know that we try to keep things as smooth as possible. I'd hate to spill my coffee, let alone the G&Ts in Upper Class!
I hope you ejoy the Air Cadets and get flying as often as possible. You'll get used to the G. Who knows, you may even get to enjoy it, as I did, and consider learning aerobatics or even becoming a military pilot - where large aircraft can and do pull G!
Scroggs