At a farbrengen, Rabbi Aronow z”l said the following story. When he was a young bochur, he was part of a group of bochurim running for their lives across the continent. Their ultimate goal was Samarkand, in Uzbekistan. During their travels, they came across a pit filled with freezing, filthy water. It had been a number of days since they had been able to use a mikveh, so of course they availed themselves of this opportunity to toivel, ignoring the discomfort of immersing in such water. When he emerged from toiveling, Rabbi Aronow said, one of the older bochurim clapped him on the shoulder and exclaimed, “Ah! Toivel bashemen ragloi nafshoi chiyah!” This story made such an impression on me. The mark of a yid, a chossid, is not that he sacrifices to serve HaShem, but that he feels such joy and enjoyment in the opportunity to serve HaShem that he doesn’t even feel that it is a sacrifice, but the greatest pleasure!