MC and excercise?

I have been juicing on and off for a week but broke down and had a bunch of bread and pasta and gained back some weight.. the other days i ate some fruit in addition to juicing. I am leaving in 2 weeks to see my boyfriend and i'm really upset that I put back 5 pounds because now I have 15 to lose.. I was wondering if I chose to do the master cleanse, if I can still workout and run my 7 miles every morning? I really want to lose as much weight as I can by September 6th but I NEED to run in the mornings.. Is it better to stick to juicing if i run that much or can i manage with the MC?
Hopefully anyone who's tried The Master Cleanse for 2 weeks can let me know what they're bodies were able to handle..
any advice would be great! thanks