Depends on what cleanse you're doing. With a juice feast you can, for the most part get through your day rather easily as you're getting enough calories to do so. Water fasting should be done when you have the time to rest as it's dangerous to go through your day to day activities when you haven't eaten in a week or more. Not to mention you get better results when completely resting.
If you're bad enough, which we have already determined you're not that bad of a case, you make the time to do it. As most men with pfs have discovered, there is NO PRICE for health. It's priceless.
Total Male Optimization "People who say it can't be done shouldn't interrupt those that are doing it"