Today, I did an impromptu circuit at the OCNP trail. About half way through, just after ascending the tallest hill of the trip, I was attempting to traverse a rock garden and I hear "PSSSSSSSSSssssssssssss" as the air was quickly exiting my front tire. I figured pure luck had kept me from getting a flat up to this point, as I'd previously chosen much worse paths to ride on as far as tires are concerned. Thankfully, I had a "field tube repair kit" (sandpaper and a piece of sticky tape). However, my pump was several years old and I guess the rubber that grips onto the valve had hardened, so it was impossible to get any air back in the tire. There was a screw device that is supposed to compress the rubber around the valve, and it wasn't doing squat, so I removed it and just held it on as I pumped. I eventually got enough air to ride on and continued to have a wonderful ride.
That's my current favorite trail. I try to hit it on Saturday or Sunday mornings as early as I can manage. Soon, it'll be too hot for me and I'll probably have to ride at the crack of dawn or near dusk. Today, it was only in the upper 70's and I was sweating profusely.