1. Blog less! Slow down or stop before real life forces you to by making your body hurt when you write. (Inspired by Farewell For Now | Justine Larbalestier.*
2. Buy, make, or improvise a standing desk. I modded my old, cheap ikea desk and brought in a high chair. Now I stand most of the time and sit when I get tired. Get a thick rug or pad to stand on.
*Yes, I am amused that I'm advising anyone to blog less.