Calling Yourself Back

I recently saw a performance where the premise was that the performer could talk to his former self at various times in his life. For instance, he told himself at 20 that he would survive breaking up with his first true love. The other calls were similar critical points of his past. He briefly mentioned the kind of time travel paradoxes this could cause, for instance, the self who bought Apple stock low and became rich would be different from the present-day self.