I had a bout of plantar fasciitis on my left foot about 5 years ago and it took about 2 months to heal. I got a pair of tennis shoes that didn't hurt. Of course I spent 3 hours trying on every shoe in the store but I finally found a pair and I wore them almost exclusively for 2 months. Then I did the exercise on the stair where you stand on the ball of your foot and slowly lift your heel up and then down as low as possible. I did it about ten times a day, ten lifts and lowers each time.
When I got it again this year on my left foot, I tried the same cure and after 4 months it still didn't abate. Finally I got an idea. Instead of doing the up and down foot lifts on the stair for ten times, I decided to do just the left foot for ten times. Surprise! I could only do four lifts and lowers. So my left arch was weak, I reasoned, that must be the source of the problem. So for the next week or two I just did the stair exercise on the left foot about ten times a day until I worked up to ten times. The pain disappeared in three weeks. A. B. Curtiss