How do you relieve exam stress?

My final GCSE exams are in a few weeks and I am stressing out! Everyone always goes on about how I should be getting A's and A*'s and I'm so scared of disappointing everyone. I really want to get into a top university like Oxford to study English Literature after my A-Levels so I really need to get good grades. I've taken loads of Maths mocks but keep getting B's (just a couple marks off an A though). I know a B is a really good grade, but it kind of feels like a fail because I know my parents expect better and if I'm aiming for those top universities I think I should be aiming for straight A's. I spend most weekends with my friends and play badminton every Thursday to try and balance my studying with other stuff, but even so all I can think about is exams. I'm so scared of messing up and I'm always in a bad mood because I'm worrying so much.

So my question is what do/did you do to stop yourself from getting to stressed about exams. Thanks. :)