An interior designer delights in transforming her own Cape Cod cottage.

A little girl from Indiana stood on the shore watching the ocean fluctuate for the first time. She felt the sand sift between her toes, and the breeze cool her face, and she understood that this was someplace special. She was only twelve, but she quietly promised herself that she would return when she was older to experience this feeling over and over.

Allyson Muller remembers this moment fondly. She was on her first school trip to Boston, and they had just returned from a whale watch in Hyannis. The promise was as innocent as any made by a young child, but nobody, least of all little Allyson, could have foreseen the essential role Cape Cod would play in ensuring her survival.

In 2018, Muller fulfilled her childhood dream when she bought her 902-sqare-foot cottage in New Seabury’s Maushop Village. It was plain, but for Muller, owner and principal designer at LUXE Haus Interiors, she saw vast potential. “I really liked the original architecture in the house,” she notes. “It was very plain, like a box, but I loved the original unit because I could see the vision of how I could make each room extraordinary. I’d rather have a plain canvas than one where I have to rip everything out.”

Despite finally achieving her lifelong goal, it was not under the joyous circumstances Muller had long imagined. Instead, designing her home provided meaning and purpose during an excruciating battle with terminal illness. “I was renovating the house after a near-death experience, not knowing if I’d ever be able to see it completed,” she remembers. “It gave me something to live for during a time when...