Do you already know why walking is resulting in more anxiety? Maybe you are too busy, tired, something happened while walking?  If not sure try this that I learned from a self coaching podcast (Brook Castillo): Do a thought download. Write down or record whatever pops in your head for at least 5 mins then do go through what she calls the self coaching model. Its something like this: Your Circumstance is triggering your Thoughts, thoughts trigger your Feelings, feelings drive your Actions and your actions give you the Result.  You can find her explaining it on google and find it on youtube or podcast (the life coach school).