Every day is tough: John manages the control tower at O’Hare International in Chicago. Prior to 2005, O’Hare laid claim to being the world’s busiest airport. (Today, Atlanta’s Hartsfield airport holds that title.) The stress is enormous. But it instantly vanishes when John’s pursues his passion—fly fishing on the Fox River, which is just down the road from his home.

John can’t take it anymore, and at 45 he’s thinking about accepting an offer to run a successful trout hatchery in Fox River Grove, where he can fly fish starting at 5 AM every morning before work. The problem is money—John’s salary would drop in half from $200,000 to $100,000.

John has tried to calculate what this would mean to his family’s lifetime standard of living. It’s difficult. John’s not the only bread winner. Kelly, John’s wife, makes $75K in a job she loves. And John and Kelly have some modest regular assets ($250K) as well as more significant ($750K) 401(k)s holdings based on their own and their employers’ past contributions. John’s job offer, incidentally, includes participating in a 401(k) with the same 3 percent employer contribution as his current position.

John’s worried that taking a pay cut would affect his future Social Security benefits. On the other hand, he knows he’ll pay less in federal and Illinois state income taxes. Another advantage is being able to work longer. John’s sure he’ll be washed up by age 60 in the air controller job, but he’s confident he can run the hatchery to at least age 65.

So what’s the bottom line? How much will John and Kelly need to cut back their spending if John goes fishing? ESPlanner can answer this question in seconds. John and Kelly need only run two input profiles—one based on John’s current job and one based on John’s alternative job—and compare recommended levels of consumption. Consumption refers to the couple’s discretionary spending—the money they can spend after paying taxes, meeting their housing expenses, making their retirement account contributions, and covering special expenditures. If John takes the new job, the couple’s sustainable consumption drops from $102,868 to $91,322. This represents an 11 percent permanent reduction in John and Kelly’s living standard. So pursuing John’s passion comes at a living standard price. But the cut—11 percent—is far below 50 percent, the percentage reduction in John’s gross earnings.

After mulling over this choice for a couple of hours, Kelly grabs John’s fishing rod, hands it to him, and says, “Take the job. Have fun. We’ll manage. Just keep it quiet at 5:00 a.m.”