1) The thin air means you are simultaneously freezing AND manage to get horribly sunburnt

2) Your shower gel explodes all over your bag

3) Nosebleeds

4) You feel like your legs are encased in cement and your lungs are about to explode each time you walk up the slightest slope

5) Your sunblock bursts all over your bag

6) Insomnia

7) Even non-carbonated drinks become so pressurised that they squirt all over you when you open them

8) You are highly likely to keel over ungracefully if you bend down and stand up again too quickly

9) There exists "gringo time" and "local-born-at-altitude" time. Thus, when the toothless shepherd says you can walk there in an hour, take this time, multiply it by three, add one quarter and multiply by another ten percent for every uphill step of the way. This is how long it will take you.

10) Your biro explodes all over your bag, coat and hands