Drink lots of water. When you feel like you _must_ eat right now (rarely happens after day two), drink a liter of water, and go for a short 5 minute walk.
Also, add a few drops of freshly squeezed lemon juice to your water. The availability of flavor is often enough to get you through the hard 5 minutes (and after day two, it is rarely more than 5 minutes).
What I noticed is that around day 7 or so, anaerobic exercise (e.g., thai boxing) becomes very demanding and hard to keep up for more than a few minutes at a time. However, it's just as easy as always to do aerobic exercise like jogging or swimming.
Never had dizzy spells or feeling of muscle fatigue (except for anaerobic exercise) - and it was also easier to get out of bed in the morning.
However, a friend of mine noted that my body goes into a super-economic mode - that I hardly lift my feet off the ground when I walk (less than an inch on average), and that my arms seem to move quite a bit less.
I'm very surprised by the lack of muscle fatigue though. I've done fasts of 4+ days 10+ times and I always get significant muscle fatigue around that point (esp. in the hamstrings).