This has been a problem for me on and off my entire meditation career and i dont know if i am ever entirely free of it. For one thing you actually do become different from long term meditation. For instance, you see people behaving reactively about this or that thing or circumstance and realize that you dont do that behavior much anymore. I have also experienced episodic states of bliss or deep calm or had this or that realization.
One of the nice things about being prideful about these sorts of things, viewing them as some sort of badge of progress or personal accomplishment, in my case anyway, is that i tend to grasp at whatever state or experience i had and for me grasping seems to shorten their life and puts you back on track, pride in this sort of thing is almost its own antidote. Grasping will ruin it. You are just setting yourself up for dissapointment.
It also helps to have a spiritual friend or teacher you respect who isnt afraid to pull the rug out from under you when the need arises.
I learned early on that if im feeling special and tell my teacher about it he is pretty good about knocking me back on my ass (figuratively speaking) and showing me where my cushion is and telling me "just do your practice".
What did the buddha say that he gained from enlightenment? Maybe nobody is special, maybe you are nobody till your nobody special
Disclaimer: I am not a theravadan buddhist i do a chan practice that could best be described in theravadan terms as citta-sati. But as ajahn dune said, all methods end in the same place.
“The truth knocks on the door and you say, "Go away, I'm looking for the truth," and so it goes away. Puzzling.” ― Robert M. Pirsig