I’ve known people who’ve been through cancer treatment before, but until my dad was diagnosed with stage IV B-cell lymphoma — a type of non-Hodgkin’s lymphoma — in October 2013, I’d never seen it up close. At the time, my mother was still recovering from a spine injury, so I became my father’s primary caregiver.

I took my dad to his appointments, followed up with his doctors and organized all of his prescriptions. I also flushed...