The beatings (PT sessions) will happen alot early on, there are gates that you have to make it through in regards to PRT's so take them in stride, put in a ton of effort and remember, the Navy paid alot of money to figure out how to get civillians in great shape in 13 weeks. Think of it as getting paid to go to the gym.
As far as the PT I cant stress putting in the effort enough, you mayt not be the fastest or the quickest on situps and pushups, but if the DI's see you busting your ass you'll be ok.
Remember the whole point of OCS is to build leaders and part of being a leader is knowing how to follow instructions. Help the whole class make it through, you can shine as an individual in acedemics.
All good gouge, except it's 12 weeks now.
Big take-aways here:
Speed, volume and intensity in everything you do.
Embrace the suck (in ways like viewing it as getting paid to go the gym etc).
Be a team player and don't let the "man" get you down (ie: don't come down on any one person because the staff is TRYING to get you to do this).
Every time you think you have it bad, just think: you get 3 square meals a day (and hot, fresh ones too). You shower daily (and if you don't, you're WRONG!). You get SOME manner of sleep each night (if you don't, you're not trying). Our boys overseas haven't showered in days/weeks, have been on watch/patrols/ops for over 24 hours, and are eating nasty MREs, so don't THINK you're going to get sympathy from your DI. You will just get killed.