Hi,
I think more lemonade would help even if you don't enjoy the taste.
The Master-Cleanse is a cleansing first and foremost, your energy level will be lower while major cleansing takes place. Working out is a bonus but if you tired I would take it easy for a couple of days.
Also feeling cold, deprest, tired is part of the detoxification process.
Be kind to your self, you doing great just take it easy.
I on day 13, yesterday seem like the world was ending and the whole fasting doesn't make sense. But I know that feeling blue and tired is the part of teh process.
I do work out but only on days where I feel up to is. So far it's been 3-4 days a week. And I don't do heavy duty cardio, yoga and light weights.