tapering thoughts

I am currently worrying about my tapering. There is a fine line between doing too much in the last 14 days before the marathon, and tapering. If one goes too tired to the start line, he could end up going too slowly and reaching the finish line in 4.5 hours. But truth be told, finishing the marathon is an achievement, no matter how long it takes. The only problem with a run of 4.5 hours, is that the body gets very tired.
My tapering is progressing as follows: yesterday I ran 12km easy, today 13km incl about 3km fartlek. During the easy sessions of fartlek I tried not to let the pace get too slow, just slower than the fast sessions.
I can't believe the race is so close!
Have a great weekend!