While my A lvls looks such a distant memory that it is almost
prehistoric when I look back now(well, maybe that's how little an
impression it left on me) 
, I can
certainly empathise with what you're going through. 
Personally, I must admit I didn't study much(and I'm not
encouraging you to take after me ), but I don't think I
did badly at all. Basically, what motivated me then was just a
matter of comprehending where I wanted to go(from aspiring to be at
the world's best universities in the near future to achieving big
goals 20-30 yrs down the road) in life and how my A lvls would open
the doors towards fulfilling those dreams. So with all that sorted,
motivation wasn't much of a problem, really(to be honest, I'm not
sure if my style would work for you if you happened to be one of
those just drifting along and haven't really thought about your
future and long-term goals).
Nevertheless, do take heed of xXStormFallXx's
suggestions(well, except for points 1 and 2 which I
personally disagree with) - however, only apply them if
you're certain those styles work for you; afterall, everyone has to
figure how he/she studies best. For me, studies were
never matters of life and death - it really is
nothing more than just one of the countless games I've played in my
life - and contrary to what most Asians would tell you, it's not
something you'll look back and dwell too much on on your deathbed.
By saying that, of course I do not mean it's totally unimportant
and that you shouldn't put in a single iota of effort, but it
certainly helps if you understand studies is only one of life's
many priorities and you enjoy the learning process more than being
obssessed with wanting to do well solely for the sake of the grades
alone. If you had an interest in what you're learning and are still
able to keep a sense of perspective, I'm sure you wouldn't be
afflicted by 'pressure/stress' as much as some of your peers are...
Afterall, I've always believed in a philosophy which puts
stress/pressure in perspective : "There's no pressure in studies -
pressure is when poor people struggle to feed their families,
people averting a natural disaster or terminally-ill patients
coming to terms with life's challenges". Hope that helps!
