There are two forms of heatstroke—classic and exertional. Classic heatstroke typically affects elderly individuals with chronic medical conditions while exertional heat stroke affects otherwise healthy people who engage in strenuous exercise in hot or humid weather.
When working outside or participating in strenuous activities take occasional breaks and mist yourself with a spray bottle. If possible, avoid performing strenuous work during peak hours of the day, between 11 a.m. and 4 p.m., especially on hot and humid days.