Simplify moment to moment life. Make habits.
Phone, meds, keys, TV remote, tablet, clothes, food, medical diary and records, appointment book, etc.; always in same place.
Simplify diet and clothing choices and develop a pattern for everything.
Experienced 5 months of chemo (non-Hodgkins's lymphoma) several years ago and, with good advice, how I coped. Entailed long days of infusion spaced 3 weeks apart, twice 4 weeks because of complications. Each time was a cycle of recovery and follow up and preparation meds and procedures. Had an apartment of medical campus where spent time for first two cycles, then spent about 1/2 the time at home.
Would get up from recliner and forget why. Think in the most simplified manner of being mindful in a small universe. When left apartment picked up keys and put in left pocket. When returned to apartment first thing was to return keys to their spot. Visualize this for every life necessity. One gets in a groove. Once wife is in a groove, be careful not to disturb the groove. One can be too helpful and confuse or upset the patient. Need to be a patient caregiver. It gets better.