Thankfully I live in the Schengen Area and crossing the border is usually no bigger deal than going to another town (aside of language on signs being different). After a while it becomes so natural that I had a very stressful moment once in the middle of a car trip from Poland to Croatia (Dubrovnik) after realizing that we will have to cross through Bosnia (for only a few kilometres actually) which is not in EU and that I haven't bought a passport. Fortunately, turned out that ID was enough to pass, although that wasn't guaranteed (and that Croatia, despite of being in EU, isn't actually in Schengen yet :P however, ID is officially enough there. It still meant that there were ridiculous border checks though).