Body Temperature Control
When hiking hours a day, being aware of your temperature and overall body feel is critical. Over time you'll gain more insight on your body and how it handles temperature regulation, but keep an eye on it.
When it's hot out, exerting yourself, you're sweating. Keeping up on water and electrolytes is key. Also taking breaks in the shade to recover.
If it's cold, you can be warm while hiking, but as soon as you stop, the puffy comes out. Be careful about sweating too much as it could be deadly if the temps are low enough.
A wide brim hat if you'll be in sunny, hot conditions. Light colored clothing. Layers. Breathable material.
Something to keep your head and ears warms. Gloves for your hands.
It's all about being prepared for the conditions throughout the day. Putting on and off layers as needed. Listening to your body on when to push and when to cruise or take a breather.