Since 80% of skin aging comes from the sun, SPF is the skincare ingredient I talk about the most with clients. Even on a cloudy day, up to 40% of the suns UV rays can still reach the Earth, so it's important to use it everyday.
Luckily, SPF formulas have changed over the last 10 years and they now include antioxidants and other skin enhancing ingredients. Glymeds Photo-Age Environmental Protection Gel 30+ is my favorite because it is lightweight and does not leave a heavy feeling on the skin.
You'll want to use a minimum of SPF 15 which will help to protect your skin for 150 minutes. The SPF levels show us how many minutes of protection you'll receive by multiplying the number shown by 10- the average amount of minutes it takes for the skin to begin burning. 1 SPF is equal to 10 minutes of protection.