Equipment Failure

I finally get out there today on my bike after a short 3 miles my left pedal arm starts to loosen. I was just starting to get into the ride when it happened. What could I do? I don't carry any tools with me, so got down and tightened the bolt the best I could with my fingers, turned around and limped back home, stopping every 1/4 to 1/2 mile to re torque the bolt.

Maybe I should see what type of took kits are available that can be mounted to a bike? I would hate for something like that to happen on a Race