well for starters You only live once was a good motto in a sense, but then it became popular and overused once it was hear in a song by the artist Drake.
1) I do not like that song particularly
2) People say Yolo when they are about to do something stupid which, to me, lowers the value of it
3) Carpe Diem is better....lol
4) I hate it when people add twitter to it and go "About to drink a handle of vodka/get a tattoo/do a copious amount of drugs/fight a bear #YOLO"
-though....fighting a bear would be cool......