Sticking with "keeping it real and casual", this is what I wore with the family for a light hike in the woods behind our house, no makeup and bedhead hardly brushed out. It was around 65 degrees and misty with chances of rain, and the ground was soggy. It was the kind of day that you don't want to get out of bed which means that's exactly the kind of day where us Garys put on our boots and force ourselves outside!
I bought this packable rain anorak from Calvin Klein I think before Emerson was even born; it's a bit snug now (especially when it's that time of the month and my bust is double its normal size), but still comfortable and a great truly waterproof layer. Under I wore a bracelet-length tee shirt; if it was colder I'd switch out the tee for my Zella running half-zip (no longer available, this one from Nike is similar). The leggings are for cold weather and so awesome I have two pairs; I wear them for hikes and morning walks but have also been known to throw them on when hanging out at home (I may be wearing them as I type this...). A pair of wool socks and these waterproof boots have me comfortably walking through mud and deep puddles without a care.