Adjust effort and expectations when the environment changes the cost and risk of a run.
Conditions rewrite the session
Heat, humidity, wind, altitude, hills and technical ground can make normal pace inappropriate. Use effort and footing to adjust rather than forcing the watch to match a flat cool route.
Shorten, relocate or postpone a session when conditions exceed your preparation.
Prepare for the route
Check weather alerts, daylight, water access and escape points. Carry suitable clothing, identification and communication, and tell someone where you are going when appropriate.
Introduce unfamiliar hills or trails progressively.
Act on danger signs
Stop and cool down for dizziness, weakness, nausea or confusion. Fainting, collapse, severe confusion or chest pain requires urgent medical help.