I don't know how healthy impromptu travel plans are for either the body or the mind - my guess is that they aren't that healthy.
Either way, I seem to be getting used to them.😄
The first one was a trip to Portugal with my mum last Christmas (which was only confirmed the day before), and the second one was my recent trip to France with my sister.
We'd discussed visiting France for a month or so before we finally decided to go. So in this case, I was more mentally prepared when my sister announced that she'd booked the plane tickets and that we were leaving the following morning.