i really understand how you feel, because my brother has the
same problem not long ago... I know its really hard to pay
attention to lectures after so many yrs.
What i recommend is always one sentence, that is "Pay 100%
Attention By Putting yourself 100% Participated!"
i.e maybe ask question whenever you dun understand. Dun need to be
paiseh (Shy) or whatever becoz everyone in the clz is there to
learn.
Whenever the lecturer say something like "do you understand", you
could juz nod your head to make sure your always participating~
Hmm... what else... well i can bring it up everything juz likdat,
but what i know is juz try to keep yourself participated in the
lecture! 
