You have absolutely no worries - it is the best gift you could give to your body...and your spirit! I have done several 40 day Master Cleanses over the years and highly recommend it. I was nervous the first time myself because not many people were doing long term cleanses then, but I did it and it was fabulous. My only regret about the first time is I stopped at 38 days because I got cold symptoms and thought that was my body telling me to go off of it...turns out that is just a sign you need to stay on longer!
The hardest part for me is getting through the first day because of cravings (although I didn't have any this time around) and I recently read that if you have a craving, just hold off on breaking the cleanse until you have a bowel movement and it should pass. We will crave various foods and substances we ate in our past as they are cleansed from our body.
Also - and I know I'm in the minority - I never could get that salt water flush down without gagging, so I just drink heavily steeped Smooth Move tea every morning and night and I still get fabulous results.
Yesterday I started a 70 day Master Cleanse...so I'll be with you in spirit! :)