As of yet I was traveling only for two months (Sept/January), but I was quite relaxed all the time. Before, in my "normal life" it happened quite often that I was upset and angry about peanuts. Especially if something that is a nobrainer and always used to work doesn't work and there was shortage of time or alike.
But as I was traveling ... nothing. Things went wrong. Doesn't matter. Have to wait 3 hours in the middle of the night cause took the wrong coach? Oh, well ... Got blisters? Okay, have to deal with it. Lost something? Okay, annoying but heck ...
But to answer your question, the first time I felt really relaxed was as I was sitting at a small pond in London (Southwark, somewhere between Canada Water and my hostel) on a small wall, drinking cider for about two hours.