too good to be true

i have always been the optimist, generally naively optimistic to a fault, and yet when something really good comes along i can't help but think: it is too good to be true, this won't last like this for long, or what's the catch?
i dislike the fact that that type of cynicism has crept and rooted itself deep within me. i hate the fact that even when things are looking up i am looking for the impending disaster.
old wounds that have turned to scars, and past mistakes, and hurts pop back into my head and essentially ruin the moment.
most of the time i try to ride out the good times and enjoy them until they fall apart, but i know i am considerably more guarded in these type of situations now cause if it all falls apart again the new wound seems to rip open all the old ones too.
and while i know it is worth the risk, it is terrifying, but if i think about it long enough perhaps not quite as scary as the alternative.