I used to be a bodybuilder way back when, and could not develop my calves. It was a real struggle getting any sort of definition at all.

Then a few years later, I was off work for a couple months one winter, and wasn't cycling through the winter at that time, so I put on heavy boots and walked, and walked, and walked (mainly dropping off job applications, but sometimes walking just to get out of the house). It was a very snowy winter which added to the challenge of the walking. Come spring ... I had great calf muscles!! I could hardly believe it ... all that time in the gym and all I needed to do was walk.

For the past couple years, we have been living in a very hilly part of the world. All my walks include hills ... can't be helped! And again ... I'm pleasantly surprised by the calf muscle development.

I am guessing about walking in the sand ... we do some of that, but it is hard to tell whether it has contributed much. I'm just guessing it might have the same sort of effect as walking in snow.