I ran about 5.2 miles this evening and due to time constraints, I did not run my usual 12 minute pace warmup. I got straight to it and I did not have a comfortable run. I still averaged just under 9 minute pace, which is about what I wanted.
I have to keep to my warmup rule. It could have been more enjoyable if I took the time to jog slowly for the first 2 miles. It took 3 miles to feel like my legs were loose.