Movie idea: a guy gets a special magical cell phone, it doesn't matter how he gets it, like a genie or a G-Man expie gives it to him, and the cell phone has the power to call other versions of himself in other timelines. These are all other versions of himself how have made different choices in life, with the idea being that each and every choice made has made a different splitting timeline, and he can talk to these other versions of himself to see how things would have gone differently.
Of course, he calls the alternate version of himself that didn't fuck up the relationship he had with his highschool sweetheart; to find that version of himself married to her, but miserable, poor, and cuckolded; also, this version is frankly really irritated at the huge number of calls he gets from alternate versions of himself. He calls the alternate version of himself who actually got good grades and got into a good college, to find an alternate version of himself who is much wealthier, but overworked and stressed out. and it goes on like that, finding that in each major decision made in his life, there was something gained, but also something lost.
He's not sure what to make of this information, until he himself starts getting calls from alternate versions of himself that had made far worse decisions than him; but are in a similar boat of wanting to know if the grass is greener on the other side (of the timeline).
Some of the alternate versions of himself are so different as to seem like total strangers. Some call him not out of curiosity, but just to harass him, in a kind of self-flagellation.
I suppose the crux of the movie would be to stop worrying about what-ifs and to appreciate the life you have, as opposed to the life you could have had.
It'd probably be a stupid movie, probably better as a short story. I just wanted to write the idea down.