Forget a hat? Cold out? Hot out? Dusty? Sweating into your eyes? This shirt trick has helped me so much.

Place your face through the head hole of the shirt so the collar comes over your chin and above your brow. Then tie the sleeves behind your head and pull the neck over your nose. This will give you a ninja mask that will protect from the sun/cold, pour water on it to cool down, and keep you hidden from all bears in the area!