Obviously, life in outer space would be no vacation -- you're out there braving the final frontier, battling meteors and malfunctioning airlocks, and knowing you'll die horribly in the abyss of space if some tiny thing goes amiss. But that's what's so awesome about it -- it's an adventure, baby! And you're doing it all in goddamned outer space!
But actually, the hardest part about life on a space station or moon base is a whole bunch of little everyday annoyances that will make your life a living hell, and not in an awesome way ...
You Have to Work Out Constantly (Or You'll Pass Out)
It is only to be expected that some amount of exercise is necessary in a weightless environment, if only because you can now rock those free weights like a boss. However, you're not going to get away with just a few wacky reps with ACME-size weightlifting equipment. You're going to work out all the time, and you won't have a choice.
"You want me to do how many reps? I can't read scientific notation."
There are two reasons behind this. One is to avoid muscle and bone turning into brittle mush due to lack of gravity. The other is a wacky phenomenon called orthostatic intolerance. On Earth, it's the reason you sometimes feel dizzy when standing up too fast. Off Earth, it graduates to being the reason your slacker ass would freaking hate space. Your body is normally able to deal with orthostatic intolerance by raising your heart rate and blood pressure until you get a grip ... but in space, your heart is a goddamn pussy. Realizing it doesn't need to do the whole "fighting against gravity" crap, it happily gets smaller and weaker, and your blood pressure drops. When orthostatic intolerance hits in a situation like that, you'll pass out. A lot.
Some of you may adapt better than others.