Wouldn't walking on sunshine burn your feet?

It's been amazingly sunny the past few days, which has given me a wonderfully uplifted mood and an "I can do this" attitude to work while enticing me outside, away from a proper desk. I keep going outside with my yay-working-well mood and realising about five minutes later that for all the good intentions, I can't actually see the words since reading from white paper in the sunshine probably requires ski goggles.

Unfortunately, and for some reason I'm not entirely sure of (I suspect excessive cycling may be to blame), my lower legs have started to ache a lot, in such a way as to make walking really, really painful - at some point early on it made me think of Andersen's Little Mermaid ("at every step you take it will feel as if you were treading upon sharp knives, and that the blood must flow"). Except my feet are fine, since all the pain is in the muscles around my shin, so the previous flowery comparison doesn't really work.

I have, however, devised one of my own:
As you can see, the ankle is actually made up of a ring of nails around a ring-shaped pressure pad directly under a spring that takes the whole weight of the leg... when weight is placed on the leg, the spring compresses (it continues down to the pressure pad, of course), bringing the tender flesh up against the nails... and also presses on the pressure pad, which triggers the nails to shoot further up into the sore fleshy bit. This happens every time I put my weight on either foot.

I've been trying to avoid walking more than is necessary.

Any helpful hints on reducing my shin-RSI would be appreciated.

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P.S. - This. Is just... omfg.