My Basic go to walking outfit is a Comfy T-shirt and black leggings, in the fall I like to carry along sweater or Chambery shirt around my waist.
This outfit is a Simple White T-Shirt, Black leggings, sweater and my trainers.
I've also found the best Sports Bra made by All in Motion from Target. It's super comfortable and I wear it under everything! It comes in sizes XS-XXL and in 16 colors!
These T-shirts from Target made by Universal Thread are a staple in my closet, I have them in almost all the colors they come in because they fit so well, perfect length and comfy.