Hey Since, didn't want you to think that I was urging you to get out there and ride in muck and pouring rain, cold temps every day or push it at this point at all...it's gotta be part of your program so that you can set yourself up for success and always, ALWAYS have fun!
I'm enjoying the holiday off-season from training and my PT/coach usually starts nudging me in January. So, I suggest (only suggest, but it's worked for me): make a plan and keep your goal in sight: use your target ride start date, total mileage and endurance (how many consistent days you've got to get in that saddle and ride 'x' number of miles), then make a reverse timeline to build up in all areas: start off easy and do as missliz recommends...just focusing on time on the road, in the saddle, pedaling with a nice, smooth steady cadence adding time and mileage each week...use the 10% rule: don't increase your weekly mileage or miles per ride by more than 10% each week...that way you build endurance, strength, and keep concentrating your riding form. I assume you want to enjoy the heck out of the whole ride experience, and get through both training and the ride itself, safely and without any injuries at all. Strength training/weights in the off-season make a big difference when you get out there on your bike in the Spring months and start tackling longer rides with tougher hills too.
When it rains, use a skull cap that you can wear under your helmet (you always use a brain bucket, right?!) that covers your ears, a waterproof, breathable jacket (Lemond has one with good reflector stripes as does Burley), layers, tights that have a good front of the leg wind/rain protection and even booties...it's really icky when your feet are cold AND wet...full finger gloves should complete this trendy ensemble...happy trails!