When do you go to the doctor?

When I was posting about my back "going out" last week, a couple of people responded with "Go to a doctor immediately!" My response was, "Why on earth would I do that?" In general, I've found doctors to be useful only if I have a problem that is very specific, unambiguously diagnosable, and can be fixed by either medicine or surgery. Specifically, doctors are notoriously helpless when it comes to dealing with back pain. So, no, I didn't see a doctor.

But it got me wondering how other people make the decision to seek medical attention. I go to the doctor when I have an earache and/or pinkeye (which happens about once every 3 years) or when I have a cough that is so bad I can't sleep (twice in the past 10 years, I think). That's about it, really. I'd go to the doctor if I broke a bone or spiked a fever of 104, but so far neither of these has happened (knock wood). I used to visit doctors somewhat more often, but gradually stopped when I realized how rarely they were able to help me.

Am I completely weird about this? What guidelines do other people use for deciding when to visit a doctor?

Incidentally, my back is back to normal now. Thanks to all who gave advice or shared similar experiences. And if anybody who is reading this HAS ever found it helpful to go to a doctor for an aching back, I would be interested to hear about it.