Slow down what you are doing. If you are walking, walk slower. If you are talking, talk slower and so forth.
Squint your eyes and blink rapidly. Make a pained look as if you don't feel well and can't focus your eyes.
Announce that you aren't feeling well. Mention to those around you that you are feeling light-headed and dizzy.
Bend your knees gradually. To protect your neck, curve your body forward and tuck your chin toward your chest as you fall. If you are sitting, slide off your seat to the floor.
Roll onto one side of your spine as you fall. Make sure your head lands softly on the ground or floor.
Lie on the ground with your eyes closed. You don't have to lie completely still. Unconscious people do sometimes move and have no control over their limbs.
When recovering, sit up slowly and let those around you help you to your feet. Give yourself some time before you become yourself again. Put your head between your knees as you rest.