Of what you have achieved that medal is the first thing that made me proud.
在你所取得的一切成就之中,那块奖牌是最令我感到自豪的.
在英语中这类句子一般是将介词短语放在句首的倒装句,按照正常语序也应该是通顺的.上面这句就可以按正常语序排列：
That medal is the first thing of what you have achieved that made me proud.