Have you every cut an apple, eaten a few slices, then left the rest for later? After coming back to finish the remainder-the apple slices are completely brown! That process is oxidation caused by free radicals.

Summer to fall is usually when I add in a Retinol. Lots of times people kind of take a break, especially if they're outside a lot, push that back in in the fall, ideally I want you on a Retinol all year round but if you haven't ever been on one, that's the best time I think to start.