Have you been writing down the one thing you like about yourself each day? If not, start now. If you miss a day, the world will not come to an end. Progress not Perfection. Progressing along - by now, you might have a nice collection of little writings about things you like about yourself.
Here's an idea. Recycle those thoughts. Copy your journal page and cut into strips - you know, like in fortune cookies. Fold each strip a couple times. Get a large jar or coffee can and decorate it (or not) to match your decor. I have no decor to speak of. In my house, if you put something down, it stays there for 5 years and becomes decor. Eclectic is a great word. My decor is 'eclectic'. Covers a multitude of sins and I don't much care about it anyway. But, I do enjoy decorating jars.
Decorate with things cut out of magazines, fabric strips, ribbons, buttons, bow, paints, glitter, old jewelry. A hot glue gun can work wonders for the craft-challenged (and the decor challenged). You can even glue the sole of your walking shoes back on with a hot glue gun to get you by til you can get your next pair of shoes!!
Then, put all your little folded strips into that pretty container. Every day BEFORE you go for your walk - or if you just can't get yourself motivated - pull out one of the strips and read it. See! You are a wonderful person with many fine attributes. Even YOU think so! You wrote it down. How authoritative. How real. How true. The Gratitude Container (GC) never lies!
Remember my 100% GUARANTEE. Should you decide to stop walking and resume your old habits, I personally guarantee that you'll get back 100% of your former life - your pain, your lifestyle, your attitude.