To the man in the checked shirt on the 7.50pm Edinburgh to Helensburgh train on Tuesday 19 July 2016 —
You were a younger me. I'd like to warn you to watch your step when you leave the train at Partick station, so you can avoid tripping over, bashing your knee, spilling the contents of your bag all over the platform, and making an idiot of yourself.
However, I am aware that this letter cannot in fact travel back in time, so this advice will be, has been and continues to be useless. Instead I offer you an apology for my powerlessness in this situation, and my unwavering support for all your future endeavours.
Sincerely,
Concerned Stranger