I do not actually ride in all conditions. I like to take the winter off from regular cycling so that I can enjoy skiing & hiking. It is very hard to be a year round cyclist in northern New England, but I am a great admirer of the few who are, the Rowell's most notably.
That said, to ride enough to be ready to race once Spring comes takes a commitment to train through every type of weather. From April until the beginning of June in my corner of New Hampshire we will get rain, wind, snow, 40F days & 85F days. I hate to ride the rollers once the skis are put away, so I must gear up physically & mentally to ride in whatever conditions the day brings. Here is what I've learned about that in the past 12 years.
1) There is no such thing as bad weather, only inappropriate clothing:
The first & key element to cycling in New England spring conditions is having lots of good clothing options. Jackets, tights, thermal jerseys, wind proof base layers, caps, booties, & all sorts of gloves are requisite. Multiples of each for different temperatures, rain conditions, & wind speed (yes there's a difference between riding into a 5 mph wind & a 15+ mph wind). Everyone has different levels of comfort in conditions, so you will have to experiment to find what works best in terms of clothing. I don't want to estimate how much I've invested in having enough clothes to meet the range the conditions. But I wouldn't be able to ride every day without my collection either.
While it is deadly to under dress, once can be overdressed on a cool spring ride too. When you are over heated you will get wet from the inside out. To avoid this adjust your layers when you can. Also, use your zipper, meaning un-zip your jacket or vest going up hill, zip up at the top to avoid getting chilled on the descent.
2) Keep the fire burning, fuel up.
Riding in the cold takes more out of you, literally. I am never more hungry than after several hours of riding in the cold. Fuel up ahead of the ride, i.e. a nice big breakfast. Stay fueled on the ride, make sure to eat something every 30-45 minutes of any ride longer than 3 hours. An old school tip is to take a baked potato right out of the oven for your center back pocket, keeps you warm on the outside & it will keep you warm from the inside if you eat it mid ride.
3) Attitude is everything. "It's a fine day to ride", "WWSKD?, What would Sean Kelly Do?", "Shut Up Legs". What ever phrase or incentive you need to get out & ride, use it. Sometimes I plan a cold hard ride to finish at a favorite bakery so that a good pastry & a double cappuccino is the incentive. Sometimes I promise myself a sauna. Sometimes I plan to make steak & frites for dinner. Any thing that gets you out to ride on the cold wet days is worthwhile.