Get in a workout
Most people complain about San Francisco hills—we love them.
Cycling long distance on flat roads is great for cardio, your lungs and endurance. But hills build muscle. They'll make you faster in the long run, and help your endurance when your energy is running low. And luckily in SF, it only takes a couple of steep hills to feel like you've gotten a great workout.
Today, go find something not flat and climb. It'll be a workout, but it's going to feel great.