You is the destination of choice of airborne bacteria, viruses, fungi and assorted parasites. With a selection of orifices for access, the thrills of grappling with an angry immune system and vast opportunities for breeding if successful, You can be the journey of a lifetime.
Airborne visitors, especially those heading to the Lungs, prefer to enter via the Nose. However, the continual flow of air in and out of the nose can make entry difficult, so the suggested method is to hang around the tip, then plunge forward during an inhalation, and grab tightly onto a nosehair before the exhalation starts. (Try not to irritate the nosehairs too much, or You will sneeze and you'll have to start all over again.) Repeat this a few times and you'll reach the safety of the Olfactory Mucosa, from where you can proceed upward into the Sinuses or down into the Lungs.
If this seems too hard, don't despair: some travellers suggest that You may be a Mouth-breather, which makes entry that much easier: instead of aiming for the nostrils and battling with nose hairs, you can just aim straight for the gaping maw underneath. The downside is that getting to the Sinuses is a little harder (you'll need to do a quick, sharp U-turn at the Pharynx). If, like most visitors, you're heading to the Lungs, keep an eye out for Epiglottis Intersection: you want to make sure you go down Trachea Trail, not Esophagus Avenue, or you'll end up in the Stomach instead. In either case, try not to tickle the throat too much on your way down, or you may end up violently expelled by a cough.
Alternately, some travellers may be introduced into You by hitching a flight on Mosquito Airlines.
This is a risky proposition, as the traveller risks being crushed by molars at the entry point and/or immediate deportation upon arrival in the Stomach region. It may be wise to avoid suspicion and detection by wearing a heavy coat of sugar or powdered cheese. This is particularly true for travellers coming from the US.
Water is good for your body. You should drink 2-5 litres of water everyday. (Just don't overdo it, you don't want to drown yourself (or your body)).
There is 72% of water in your body. Cool huh?
The bloodstream is by far the most common method of getting around You, as the network of arteries (from the heart) and veins (to the heart) circulates throughout You, allowing fast access to every nook and cranny. The main danger is the presence of white blood cells (see #Stay safe), a famously xenophobic lot, which have been known to attack innocent tourists without warning.
By spinal fluid
For the hardcore traveler, the spinal fluid provides an exciting alternative that pumps out at the massive bandwidth only the Backbone can provide. Access is difficult, as the Backbone is encased in a solid layer of bone, but it's worth the trouble, since once inside you've got a ticket straight into the mysteries of the Brain.
The main danger of going spinal is Spinal Taps . If you hear the amplifiers getting cranked up to 11, get out as fast as possible, or risk spontaneous human combustion!
Lung transplantation is very expensive, although it can substantially improve quality of life. Two-thirds of the costs are incurred after transplantation.
A variety of comfortable resting places can be found throughout Your body.
White blood cells (leukocytes) patrol Your bloodstream, engulfing and digesting hapless tourists who cannot produce correct identification on demand. Be sure to alter your protein signature to blend in with the locals if you see any approaching. There is a more dangerous threat at hand - a multinational terrorist cabal known as Medicine. On occasion, Medicine will initiate a brutal massacre in areas frequented by tourists. It is best to leave via Nose or the Colon border.
After You have been taken care of, there are still several billion other sacks of protoplasm left to explore. Some options include: