In the US, daylight savings time ends this weekend. The day length doesn't change, but Americans reset clocks so that it gets light in the morning and dark in the evening an hour earlier.
I read a news story about a study showing this change leads to a dramatic, 168%, increase in pedestrian deaths during the evening hours, around 6PM. Drivers and pedestrians are not yet used to the early darkness, increasing the number of vehicle pedestrian accidents.
Work schedules force many people to exercise in these evening hours. If you walk, run, or bicycle in the evening after work, don't give up your exercise. After all inactivity also has health risks. Just be aware of the risk of walking, running, or bicycling in this evening darkness.
Make an extra effort to both see and be seen. If you walk after dinner with your children, make sure that they are extra careful about traffic. Carry a flashlight, or wear one of those lights that straps onto your forehead. If bicycling, make sure your bike is equipped with lights and reflectors.
Wear light colored clothing which is more easily visible than dark clothing. Better yet, wear a reflective safety vest. A reflective vest similar to those worn by highway workers will allow you to be seen by motorists. If you want something more fashionable, there are many active wear jackets, pants, and hats made of highly reflective fabrics. This clothing will both help you keep warm as the weather cools and allow drivers to see you when you are exercising after dark. You'll look good too!
Continue exercising but make sure drivers can see you. If you are driving, be extra careful to watch for bicycles and pedestrians.