I'm just under three weeks and I'm still pretty knackered if I do much (my job is pretty labour intensive so I expect not to go back for a couple of weeks yet at least). Endless milkshakes have helped though (and stopped me from losing much weight, jury out on whether that's a good or bad thing!) it doesn't help that when I'm out of my normal routine my body clock gets way out of sync so I suspect that I won't actually feel back to normal until I've been back at work for a week or two (although I suspect the first week will be hell!)