Find out, why I'm so happy today.
1$\begingroup$ Congratulations! No small feat :) $\endgroup$– ricdesiApr 24, 2017 at 19:01
shown in the rightmost cell of the second row, for each cell, we need to take the difference of the two cells above it. The resulting configuration is:
Now we need to
Take the letters corresponding to the numbers in order, yielding: CELEBRATING MY ONE HUNDRED PUZZLES.
(Note that some numbers are missing: namely, 15,24,27,31,33. I guess we simply ignore them.)