Whenever a character does certain things _ there is a list of these in the book, but it includes Jump, carries a weapon, combat, lies, etc. - or things like them, the character rolls a d6, taking that many points against their stress track.
Whenever a character does certain other things _ there is a list of these in the book, but it includes time with friends, taking a shower, sex, meditation, etc. - or things like them, the character rolls a d6, if even adding 2 points, if odd adding one point to their stress track.
A stress track is based on the character's four physical attributes, STR, COOR, AGY, and END. Four pools of points equal to the character's attributes are made - and when you make the stress track, you have to choose Fight or Flight. Points are deducted from first COOR points, then either STR (Flight) or AGY (Fight), the either AGY (Flight) or STR (Fight), then END. Each level after the top has bad consequences ranging from hair/fur falling out to catatonia, and the lower you go, the worse your TN is.