Still plugging away. Wow, I've been working on this for quite a while,
and I don't feel too fatigued yet. Here's what I tried:

• Munch on things regularly to keep a good sugar level. I brought
  plenty of apples and bananas, and I've been raiding the bread and
  crackers.
• Drink plenty of water. This also forces me to get a bit of
  exercise. I find I get very thirsty when I think… <laugh>
• Set my computer to force a 5- to 10-minute break every hour.
  Microbreaks (15 seconds every ten minutes) are also useful. I don't
  find myself losing track of ideas, and I can stay on track better
  when I know regular breaks are coming up.