You do not have to go the long haul to accomplish your goals. You can do another cleanse later!
It took me four years to attain my goal, turning 50 with a clean pink colon! That included a couple of very long (30, 60) day fasts and lots of other do-dads.
I did a series of 10 day fasts with ten days cleansing diet between. That was very rewarding!
A very long fast should be supervised, as it can bring on some pretty hairy metabolic changes (like hair loss). I could not have done it without my wonderful naturopath.