I've been LCing for over 3 years, and I notice weight bearing activity seems rather hard on my sugar levels. Light walking and jogging is perfect for my metabolism, it augments my fat burning (I tolerate carbs better, I "feel" more ketogenic, appetite is more controlled, so on). If I do vigorous walking carrying heavy things, or heavy lifting, I often start shaking (implying my bod is trying to crank out sugars). However, if I eat a bit of carbs the day before I have no troubles and usually have wonderful energy. One night I drank half a can of regular soda (accidentally). The next day, my energy was perfect doing things that normally I can't do without getting a drop in sugar and shakiness.

Then again, as I said earlier, I suspect my metabolism isn't balanced (in catabolism/anabolism). If I ate more and put on fat, this intolerance to intense effort might go away. I notice it does get a lot better if my metabolism is oriented toward fat gain (from eating a lot) even if carbs stay low.