Ok, so I haven't ever done the master cleanse (I prefer juice fast) but...

Don't stop! This time is probably going to be the hardest for you and I know that I went through several days of feeling a little "foggy" but, honestly, it will get better. After the first week it is amazing how wonderful I felt (yes, clear headed and almost sometimes euphoric...)but it took a little bit to get there--especially since right now you are detoxing.

It sounds like you have a pretty active lifestyle which should make you feel a little better. My goal is to hike every single day when I start my fast at the beginning of May--which, I must say, is because you have inspired me to do so.

Anyway, I really think that you should continue--even for the sense of feeling that you completed what you started out to do!