athlete -n. a person who is trained in or good at sports, games, or exercises that require physical skill and strength

challenging -adj. difficult

isolation -n. the state of being in a place or situation that is separate from others : the condition of being isolated

physiological -adj. characteristic of or appropriate to an organism's healthy or normal functioning

endorphin -n.a hormone released by the brain and nervous system and causing a number of physiological operations

bike -v. to ride a bicycle

hiking -v. to walk a long distance especially for pleasure or exercise : to go on a hike

bungee cord -n. a very strong rope that can be stretched and that has hooks on either end