This is my trick - once I have done my research, sought lots of feedback, and made up my mind, I don't ask anyone for any more advice (or to seek validation, because let's face it, this is what you're really looking for). I also don't tell anyone about what I'm doing and I stop reading the paper and watching the news. Seriously. Once I've made a firm decision - based on the best information I've been able to gather at that time - I then stick with it till the end of the search-contract-settlement period. I don't tell anyone about it till I've wrapped things up.
What happens if something massive changes that should alter my decision, like WW3 or a huge financial crisis? Well, I figure news that big ought to get my attention anyway. It's important to be confident in what you're doing and stay the course...and this is how I do it, for better or for worse. Otherwise there's too much second guessing and flip flopping. If you've just done months of analysis, the last thing you want is a pessimistic know-it-all upending all your research based on a few bitter remarks. I've been through it all too much myself.