Yeah, the winter is important for fitness, but you can't neglect the ball.
Is Darren Huckerby one of the best players in the world? Of course not! Why? Because football isn't based solely on speed. You have to have touch, class, be able to pass and dribble and shoot the ball. Valeron with Spain is slow but he's one of the best players in La Liga and a Spanish international because he's so good on the ball.
You can't just run. Sure, do the running futbolista mentioned, but you also have to work on the ball. If all you do is running how is that different from training for track?
Just stand outside, juggling the ball. Get touches, don't let yourself get rusty over the break. If it's too cold, go to a local gym and play in the baskeball courts. Just pass the ball of the wall again and again, practicing your passing and receiving.
Imagine if Thierry Henry finished with the Premiership, then didn't do anything but run then was expected to straightaway start playing at a high level with a ball again? It wouldn't happen.
However, if you start getting sick at all, take a break immediately. I started suffering in a very cold October, but I played on, kept training in the cold and rain, and I went from sick to sicker and I got this cough at the beginning of November that has yet to leave me. It makes football a very difficult thing as every time I run the cough gets worse, so you can imagine the dilemna.
This just shows not to play through sickness, especially at this time of the year, as it just hurts you worse down the road.
If you aren't in the mood to train in a hard manner, what I recommend is a fun game called goalie wars. It's best on a futsal court or in a gym with mats behind basketball goals. The game is played by just two people. They just try to score on eachother, haha. Like person 1 would shoot on person 2, then person two could save with their hands, then control and shoot. Now you only have 3 touches and the ball can't stop, so it's fast paced and you get a bit of fitness work in, but it's also fun and you can practice all sorts of shots, as it's easy to get into bad positions for either player so you practice chips and bent shots and hard drives and lobs. It's better if you have goalkeeper's gloves, but it's fine if you can't.
Hope this helps with your winter footy.