i work 2-3 days a week as a gardener so yeah i'm pretty active, i also am divorced and have 3 children to look after. i started my fast on a sunday so i had 3 days to get over the worst before i was back at work. when working i drink mint tea with added maple syrup for energy, i also take a teaspoon of maple syrup as and when my energy levels flag really badly, just to get me over it.
if it's any consolation it does get easier the longer you fast :)