Maran Rav Gershon Edelstein zt”l, Rosh Yeshivas Ponovezh, was very careful for decades, since he was young, not to leave the city of Bnei Brak. Why?
The reason was singular: His blood pressure was sensitive and could rise from any abnormal activity, especially traveling by car. According to his calculations, if he went on a round trip to Yerushalayim, it would raise his blood pressure and weaken him, thus preventing him from delivering shiur to his talmidim.
As is well known, Rav Gershon, for 80 years, delivered a shiur every single day without exception, even on Shabbos and Yom Tov, until his last day. The image of “adam yomus b’ohel” was publicized, showing the rosh yeshiva delivering a shiur in an intensive care room on his last day.
There were deviations – every year, Rav Gershon made it a point to go on Chol Hamoed Pesach to Mishnas Akiva-Bais Shmuel in Mattersdorf to meet talmidim and deliver them a shiur. Likewise, during Chol Hamoed Sukkos, he would go to Sha’arei T’vuna in Ramot to meet talmidim and deliver words of encouragement to them.
{Matzav.com Israel}