Even in the most mundane of situations we sometimes feel that our shields are not holding as well as they could. This spell is meant to reinforce your inherent personal protection, to protect you from things that might mean you harm.
Ground and center yourself, and draw forward a small amount of energy. If need be, you can light a candle to help with focus and raising energy. Picture in your mind the bubble of personal space surrounding you. Hold this image as you steadily feed the spell ingredients and intent into the bottle, all the time picturing your bubble or shield becoming stronger, thicker, or more resilient. Cap tightly and wear as a pendant or place in a space that it personal to you.
Source: A Spell to Protect Yourself