Lie #1 - You can be comfortable at sea.
Alisa and I were both lucky enough to work on commercial fishing boats in Alaska before we went cruising. Those boats were BIG - 90 to 150 feet, and, even though they were working boats, pretty luxurious - they didn't roll anything like as much as Pelagic, and we could always get a hot shower after our work was done. Even so, we spent a significant amount of our time on those boats being slightly uncomfortable to completely miserable. We figured that was just part of going to sea.
But a lot of cruisers seem to have this slavish devotion to being "comfortable" on their boats, and people tell us they don't like passages because being at sea for a long time is so uncomfortable. We (subtly, I hope) roll our eyes at this. "Comfortable" at sea - WHATEVER! Forget about it. People who want to be comfortable on their boats end up sitting in marinas. Sailing long distances across the ocean in a small boat is an adventure, it's a damn spirit quest, it's an act of self-directed will so intense as to be almost mythically beautiful. Who cares if the sheets are salty, or you're vomiting over the side?
Lie #2 - You will have lots of free time.
Here, our experience may not be representative at all, since we set out from home with a 10-month old child, our boat is 27 years old, I have continued to work on and off while we lived aboard, and I've also pursued the time-devouring task of trying to write as we go. That's a lot to tackle. But, understand this, anyone who would go to sea full time for a year or two: there is NEVER a time when we don't have some desperately long to-do list of boat maintenance jobs hanging over us. That list is usually posted over the chart table, for all to see, and we long ago gave up any hope of ever seeing the end of it.
Lie #3 - Technology is your friend.
I'm no Luddite. I love roller furling. I couldn't explain why anyone would want to sail without GPS. But, the hyper tricked-out, super-complex state of cruising yachts that people take as a given has nothing to do with what's best for going to sea. It's a state of affairs dreamed up by yacht gearmakers and advertisers and the sailing magazines that serve them. Fancy stuff like watermakers can be nice, but it's a mistake to get stuff like that until you've been cruising for a year or three, you're on top of all the basics, and you know that you really really want a watermaker. Otherwise, you'll turn out like so many who were convinced that you "gotta have" a watermaker to cruise, and you'll find yourself wasting money and time (see #2), trying to get the thing to work, when you could have just been taking a nice dinghy ride to get a few jugs of water.
The same argument applies to networked electronics, big freezers, gensets, long-range internet access, and a lot else. All those things can be nice, individually, but paying for and maintaining and learning to use all that stuff will, collectively, keep you from a lot of sailing. Read some Bernard Moitessier before you go sailing, and go sailing to be free!