I expect what you're not aware of would fill several books, Dursely.
I've been lucky enough to fly to space twice.
For the last several years and culminating in six months in orbit next year, I've been training for my third space flight. This one is almost in a category completely different than the previous two, specifically to live in on the space station for six months, to command a space ship and to fly a new rocket ship.
Other anatomical changes associated with long-duration space flight are definitely negative: the immune system weakens, the heart shrinks because it doesn't have to strain against gravity, eyesight tends to degrade, sometimes markedly (no one's exactly sure why yet). The spine lengthens as the little sacs of fluid between the vertebrae expand, and bone mass decreases as the body sheds calcium. Without gravity, we don't need muscle and bone mass to support our own weight, which is what makes life in space so much fun but also so inherently bad for the human body, long-term.
Our training pushes us to develop a new set of instincts: instead of reacting to danger with a fight-or-flight adrenaline rush, we're trained to respond unemotionally by immediately prioritizing threats and methodically seeking to defuse them. We go from wanting to bolt for the exit to wanting to engage and understand what's going wrong, then fix it.
Our three big emergencies are fire, loss of pressurization or contaminated atmosphere. Any of those things in a spaceship are very deadly and time critical. Everybody's trained, but I'm the commander of the ship, and it's up to me to decide.
The Nile, draining out into the Mediterranean. The bright lights of Cairo announce the opening of the north-flowing river’s delta, with Jerusalem’s answering high beams to the northeast. This 4,258 mile braid of human life, first navigated end-to-end in 2004, is visible in a single glance from space.
Positioned on my dresser, that white-as-snow rose is a personal message to me. It speaks of unfinished business. It whispers, I can find you. I can reach you. Perhaps I am watching you now.
Humour in its highest reach mingles with pathos: it voices sorrow for our human lot and reconciliation with it.
I know no real worth but that tranquil firmness which seeks dangers by duty, and braves them without rashness.
Hell man, I know very well you didn't come to me only to want to become a writer, and after all what do I really know about it except that you've got to stick to it with the energy of a benny addict.