I mentioned in another thread that my belief began before I could formulate it as belief...more like I came into this life knowing.  I have spent my time trying to figure out how it works and to understand how much more I can get out of this lifetime with that knowledge...sorry, I know this isn't much help.  It might be beneficial to think of the afterlife as fact and work on eliminating things that don't support it, instead of trying to prove a positive.  I don't find myself seeking verification, rather I seek connections and all the verification comes with the found connections.

I did have a singular event that brought me as an adult to the point I am now, but it wasn't so much a new found belief as it was a redirection and focusing of effort on the topic of the afterlife...which term actually doesn't really fit my belief...our life is active here as well as "on the other side" right now so "after" isn't very accurate.  Our souls, of which our conscious, living body holds only a part, are doing so much more right now than reading or typing on this messageboard.

As far as what I sense that corroborates my knowledge or belief is a conscious understanding of my own physical responses to various stimuli...meeting an individual whose soul I know results in a gut feeling that either spreads warmth (positive) or cold (negative); hearing or reading a "truth" results in a warmth emanating from my heart and spreading throughout my body...really profound truths bring a gush of tears; meeting a soulmate seems to not only cause warmth from the heart but also a halo of warmth around my head which seems to energize and elate me...and these effects/impressions/responses I receive are never wrong and they are often (regarding the first and third) mutually felt.  I think these responses are available to everyone; some are simply more attuned to them or look for them...psychics and other extremely intuitive people sense all this and more without conscious thought.  It seems to me that those in tune with these sensations and their meaning have no choice but to believe in the afterlife or the "other side" as it is simply a change in location of one's conscious awareness.

I hope this helps...