It would appear as though you have found a way to manipulate the time and space continuum and make both yourself and your future self meet.Or since you're reading this in 2021 it's yourself and...
Dear 18 year old Mike,
Happy Birthday! It's December 11, 2011. I'm bored as fuck sitting on the couch using stumble upon and I've found this website that'll send this letter in a year...
labas
Cha, aš rašiau šitą laišką dar 2011-09-28.
Džiugas
Felicidades