If you are finding your normal running time in the morning is getting darker each day, it is that time of year to either where a light on your head so you can see, or opt for other types of cardio activity. Here is a way you can do both while it is still not TOO dark -- it should at least last you until we roll the clocks back to end daylight savings time.
Spend about 15-20 minutes on non-impact cardio options to loosen up. Or, if you are limited to a treadmill, start your run / warmup on the tread mill before you hit your normal run. This will get you outside about 15-20 minutes later, so the pre-dawn light will at least be helpful for seeing where you are going if you prefer to train outside.
Warmup With Non impact Cardio: 5 min bike or elliptical or rower warmup 5 min tabata interval (20 sec sprint / 10 sec easy) on bike Repeat on rower or elliptical if available. Total 15-20 minutes of using different machines for 2-3 sets of tabata 5 min intervals. Then go for a run. The distance is up to you. Our morning run today was 4 miles Then we followed it up with a big swim workout (indoor pool) Add a swim workout if you are training for something (event / military / special ops) or skip all the above and just swim if you have a pool available. Swim 500m warmup repeat 10 times 100m free at 6-8 strokes per breath 50m CSS at goal pace (or breast stroke)