Birkinstock sells a suport for shoes and there are some inserts that are made soft and some hard, it depends on your feet though.
I have tried the birkinstock sandals and my feet do feel so much better, but somedays I do use my gymshoes with support (the hard ones) it varies with everyone and check out birkinstock sales on the net. do your exercise too for the feet. I am 31 yrs of age, and this is no fun!!! Linda