People have long saved for life’s biggest milestones: buying a home, getting married, and retirement. Some workers are also putting money aside for something they hope never happens: burnout.

Last week, Mary Kane handed in her resignation letter.

After six months of feeling exhausted, irritable, and increasingly burned out in her job as a senior marketing manager, the 54-year-old Minnesotan decided she’d had enough.

Unlike many workers in a similar position, she wasn’t terrified about how she’d pay the bills once she quit. For years, she says, she saved about half of every paycheck, building what she now calls a burnout fund.

‘Really intentional…