Rav Schachter was Maspid him quoting a Gemara in Yoma. The Gemara says that Hillel is Mechayev all the Aniyim in Talmud Torah because Hillel was so poor and yet still learned. Rav Schachter says that R’ Nosson Tzvi is Mechayev all of us because he managed to learn so much even with terrible physical afflictions.
If the mods will let it through, I will post a link to R’ Schachter’s Hesped (YUTorah). Rav Schachter is the first 10 minutes or so. I’m not sure who the last 8 minutes is.