CAN YOU EVER BE SURE YOU'RE MAKINGTHE RIGHT DECISION? Should you stay in a comfy job with little chance of advancement-or take a riskier one in which you could make lots of money but also wind up on the street? Should you listen to a doctor who advises surgery-or trust another who tells you to wait and see if your condition improves? Should you remain in a cozy relationship without much spark-or cut your losses and search for your...