Help for conditioning feet for hiking.

I have been taking increasingly longer, steeper and faster walks…but my feet don’t seem to condition as well as my leg muscles and cardiovascular system.

As the exercise becomes more rigorous, I’ve experienced regular blisters, blood blisters, and calluses in odd places.

I think that my shoes/hiking boots are OK, and if I walk slower, these problems don’t seem to develop. Other than slowing down, are there any ways to condition my feet to withstand the exercise levels needed to maintain high levels of cardiovascular conditioning?

Your suggestions are appreciated.