pavlovian response

i was on the train today for pretty much the first time this month. on my way home, although i'd been in having lunch with a friend and doing a bit of leisurely shopping and then having tea in a tea house, in all, RELAXING, i got a strange bone-tiredness on the train on the way home. it hit me that it was a pavlovian response. a residue of how tired i've felt coming home on the train over the past year. my body just instinctively reacted in that way when it found itself on the train at the end of the day. i had to actually talk myself out of the tired feeling, as there was no way i could have felt tired after the leisurely afternoon i'd had. i hope it passes, as i'd like to be able to ride the train again like a normal person!