When I was a kid, I thought it would have been kewl if I could know what other's lives where doing in their own parallel universes.
When I was in high school, I used to play the game "What your alter ego is doing right now?" with my schoolmates, and they were pretty amazed by the very creative way I was explaining them what they were doing in their other lives.
What's interesting is, the more I grow up, more scientists proves that what I always thought was completely true, despite the fact I was imagining those fact, based on their actual decisions.
Let's go deeper in that, shall we?
Reading on the internet I saw all kind of stories, for example, meditation can merge with your other self's and make you feel what the others "you" are doing.
That would even explain better the "deja-vu" factor.
In simple words, there are bilions of degrees of worlds, and in many of them, there are the ones where you had success, or what you always wanted in life. That would make you feel jealous of yourself, but be glad, you can still make it happen in this world if you truly believe it, you should just ask it to the successfull you how he did managed to, and you will aswell.