When I was ten years old (in 1963), I had a plan for my life. After high school, I would go to the US Air Force Academy, followed by flight training (jets, of course). Later I would go to test pilot school with the ultimate goal of becoming an astronaut. I was too young for Apollo (and for Vietnam as an officer and pilot), but if it had worked out, I would have been an Air Force pilot in the late 70's and astronaut-ready by the mid-80's. The plan fell apart when I was 12 and started to develop severe myopia. The Air Force Academy and flight training wouldn't allow corrective lenses (of course even if I had 20/10 "Yeagervision" there are any number of other things that could have killed my plan, but hey, it was a fun plan while it lasted).
Packing for Mars (by Mary Roach, subtitled "The Curious Science of Life in the Void"), I understand better than ever that the astronaut's life is much more complicated and less enjoyable than you might imagine. Maybe this wasn't the life for me. Of course I knew this at some level from a lot of previous reading about space flight, but with the exception of some astronaut memoirs (especially Mike Mullane's down-and-dirty Riding Rockets), they don't go into much detail on the discomforts and inconveniences of space flight. Mary Roach does, and she does so with a writing style that is informative, colorful, personal, and often downright hilarious. I was laughing out loud at least once in every chapter. Her writing style often reminds me of Bill Bryson. She explains things clearly, but emphasizes quirky details and people. While the situations are often funny, she obviously respects the people and the work they do, so it never comes across as snarky - she's often laughing with the astronauts, cosmonauts, and other space workers.
Of course she covers the required "going to the bathroom in space," but she also covers the psychology of isolation and confinement, general problems of zero-G (including bone loss and vomiting), crash testing (with cadavers!), animal testing, Earth-based mission simulations, hygiene, and the ever-intriguing questions of sex in space. On the latter topic, she isn't able to come up with any hard evidence (sorry) that it has happened, but you can't say her research wasn't thorough. Considering that someone might have "done it" in a zero-G parabolic test flight, she tracks down and watches an obscure porn movie that was rumored to have had one scene shot on such a flight. She uses a fluid dynamics argument (sort of) to conclude that while the scene may have been shot in an airplane, it was not shot in zero-G. Read the book for more. You will also learn some interesting things about dolphin behavior and anatomy, since these marine mammals have to deal with some of the same issues as zero-G astronaut couples might encounter.
The author interviewed astronauts, cosmonauts, and all sorts of researchers, and her field trips included a flight on the "vomit comet" (she didn't vomit, thanks to "good drugs" they give you) and a trip to Devon Island in the Canadian Arctic, where NASA conducts simulated lunar and Mars missions in a remote, desolate, cratered environment that's about as close as you can get to Moon or Mars terrain on Earth. NASA and the US astronauts seemed to be the most "uptight," and the Russian cosmonauts the most frank in describing uncomfortable stuff. One exception was Jim Lovell, who was was unusually open, especially when she asked him about Gemini 7, in which he had spent two bathing-free weeks in the tiny Gemini cabin with Frank Borman, who apparently could be a rather cranky and difficult guy. Lovell proved he was brave enough for Apollo 13 by spending some 23 days in space with Borman (Gemini 7 and Apollo 8 - Borman was sick most of the time on Apollo 8, though it wasn't admitted at the time - so perhaps a bit of crankiness could be forgiven).
I read the Kindle version of the book, and I found it was valuable (and funny) to read most of the footnotes, which required a "click" for each one. Some of the funniest comments are in the footnotes. A very good book, even if you're not especially interested in space.