The Rebbe explains that refraining from Torah study due to illness is like refusing medicine because one is sick. Torah itself brings healing, and one must persist in learning—at least the daily portions of Chumash, Tehillim, and Tanya. The Rebbe encourages optimism in recovery and expresses hope for good news, both spiritually and physically.
https://www.torahrecordings.com/rebbe/igroskodesh/015/009/5487