1

You can forgo air for one round beyond 10+Fortitude rounds, after which you suffer X points of Constitution damage each round, where X is the number of rounds since you hit your limit.

1

You can forgo water for one hour beyond 30+Fortitude hours, after which you suffer X points of Constitution damage each hour, where X is the number of hours since you hit your limit.

1

You can forgo food for one round beyond 10+Fortitude days, after which you suffer X points of Constitution damage each day, where X is the number of days since you hit your limit.

1

You can endure constant moderate physical exertion (i.e. moderate physical labor, forced marching, etc.) beyond your Fortitude in hours, after which you suffer X points of Constitution damage each hour, where X is the number of hours since you hit your limit.

1

You can endure constant strenuous physical exertion (i.e. strenuous physical labor, swimming, climbing, etc.) beyond 1/2 your Fortitude in hours, after which you suffer X points of Constitution damage each hour, where X is the number of hours since you hit your limit.