Have you been having punctures, or do you worry about them?

We had thornproof tubes on our bikes when we were kids but we were riding around in a new desert development full of goatheads.

If you carry a bike pump, you may not already know this, but usually you can convert it from Schraeder to Presta by unscrewing the cap on the pump head, pulling out the rubber seal and the plastic bit that would push on the Schraeder valve, flipping both over, and putting it back together. One way you get the big diameter seal and the little nub to push on the Schraeder valve core, the other way you get the little diameter seal, and the Presta valve is opened by the pressure of the pump.