Let me tell you about my first trip. There was a moment, a single moment, where it began to set in what was about to happen to me. In this moment I had time to think, "OH GOD. PLEASE, NO." And then it tossed my consciousness against the wall of the universe so hard it shattered into ten trillion shards.
Years after it was over, shockwaves from that trip continue to reverberate through my life. The undulations became subtler with time, but even now, if I tune in, I can recognise it. There were times I wondered if I ever really did come back from it. I eventually found peace with that paranoia when I realised that I didn't.
And it's great.
EDIT: and to clarify, no you are not going to lose your mind if you take LSD in a responsible manner, which includes research, an appropriate beginner's dose and ideal set and setting. However, even then, during the experience itself ANYTHING could happen. There's really no telling for someone who's never tried it before. There are simply too many variables. It's a truly alien landscape. Others in the thread are saying not to stress which is fine; I simply want to add the caveat from my own experience, don't take it too lightly either.