Side effects ~ do we just get used to them?

So we all take these meds, everyday for the rest of our lives.  I can't remember what life was like before taking them, so how do I know whether I am having side effects?  Do we just get used to living with them?  

At the end of the day it's really hard to say I can't live with these side effects for the rest of my life unless they are really really bad... the tiredness, stomach problems and dizzyness, I CAN live with it but should I? How much is it affecting how I live life?

Anyway now I am starting Keppra it seems like it could be a new start, maybe my stomach problems will get better and I'll get seizure control... the idea of reducing my Lamotrigine in a few weeks time comes with mixed feelings... hope that it could be the one and fear because it could lead to more seizures.