Let them lie down a bit so blood returns to their brain
Raise their legs above the level of their heart
Loosen their belt or belly trimmer. Stop watering them, they're not plants
The falling is the body's way of getting the brain to the level of the heart
It takes a few moments to get conscious again.
Low blood sugar can also lead to it
Dehydration, extreme exercise(This happened to me)
Severe pain can cause people to faint also