I cannot emphasise this enough - warming up before exercising matters!
An effective warm up prepares the body for the physical challenges it is about to meet (if the workout is demanding enough!) and the mind for the focus that is now required of it. Warming up is also a part of the workout; it is not an add-on. Once the warm up starts, so does the workout. The road to fitness is about to take a few more steps and the game is on.
All of the above matters in the gym, but it matters so much more when exercising outdoors, particularly in the winter and on cold days. So, particularly at this time of year, warm up, warm up, warm up!
Your body and mind will thank you for doing so.