Workers are feeling very ambitious these days: one in three plans to retire after age 65. In the 1990s, just one in 10 did. In reality, though, many older Americans today are retiring before they’d planned, resulting in lower monthly Social Security checks, slimmer 401(k) accounts, and more golden years to pay for. There’s no shortage of research looking into what derails these plans. But, for the first time, a new study ran a statistical horse race among the various reasons known to impact older workers’ decisions. Health issues finished first in the race, followed by layoffs, and a spouse’s early retirement. In an ideal world, eliminating these major shocks, along with a few less prevalent shocks that were also analyzed,…