It's 5 p.m., the deadline for an important work project is at 6, and all you can think about is the fight you had with the next-door neighbor this morning. You're dwelling, says Susan Nolen-Hoeksema, PhD, a professor of psychology at Yale and author of Women Who Think Too Much. "It's natural to look inward," she says, "but while most people pull out when they've done it enough, an overthinker will stay in the loop."

Ruminating regularly often leads to depression. So if you're prone to obsessing (and you know who you are), try these tactics to head off the next full-tilt mental spin cycle…