It's inevitable that plans will go awry and you will have to deal with some sort of problem when travelling. You might miss a bus, a hotel will be over booked, or a flight delayed. The list of things that can go wrong on trip is endless and something will probably go wrong. Instead of flipping out and getting angry about how you're trip is ruined you should instead try and turn whatever it is into a good day. Maybe it won't be as good as the day you had planned, but it will beat being at home working.
You miss a bus - spend more time walking around watching people.
The hotel is over booked - hopefully the next one you find has more character anyway.
Your flight is delayed, well that just sucks but catch up on some reading.
Most of the time when there is a problem on a trip, it's insignificant in the grand scheme of things, but if you let it bother you too much all you're going to remember on that trip is the inconvenience. Sometimes it really is just a state of mind that you need to work towards to be able to let it go and enjoy yourself despite the situation.
Don't sweat the small stuff.
