You can do this by working part-time or seasonally in retirement. You could also consider offering childcare or household help to family members in need. Or you can endeavor a new project that requires focused time and energy.
Keep in mind that if you start collecting before the year you reach full retirement age, working can impact Social Security benefits—with as much as a $1 reduction for every $2 you earn more than $16,920 in 2017. And consider work-related costs (commute, lunch, equipment, clothing, etc.) when planning your retirement budget.