Marnie O. Mamminga

On her "Medicare Birthday," author Marnie O. Mamminga celebrated by swimming to an island in Big Spider Lake near Hayward, Wis.

No easy feat for a 65-year-old.

The lake, where Mamminga spent nearly all of her birthdays, is home to Wake Robin, a cabin her grandfather built in 1929. The vacation home, made of tamarack logs, is the setting of Mamminga's first book Return to Wake Robin: One Cabin in the Heyday of North Woods Resorts.