Vary your daily distance
Running the same distance every day can lead to burnout at the very least and very possibly injury and down time. It can also make you slow. Mixing up your workouts adds interest and produces better results. Pick a day to shave a few miles off your workout and run faster for the shorter distance. This will help maintain and develop fast twitch muscle fibers and your mind and body will appreciate having that cup of latte an hour sooner than usual.
Take a day off
Even God takes a day off. It is good for the mind and soul to have a day of rest to look forward to. A day off can go a long ways towards avoiding burnout and the extra time can be used to catch up on life's details that seem to get left behind during a difficult training regime. Worn muscles need a day to heal and at least one day off will help with that recovery.
Run in the morning
It gets dark early in the winter and running in the dark can be a real bummer. If you are one of the lucky ones blessed with a flexible working schedule try going to work an hour later and getting your training done first thing in the morning. That way you will be sure that family and work problems won't overcome your training goals and force an unwanted day off. There is nothing like an invigorating run in the morning followed by a hot shower and the feeling of satisfaction that the day's workout has been checked off.
Stay out of the cold a couple of days
Join a health club and do some strength training. It takes strong muscles to run well and some quality machines can help with that in the winter. There are some days that are just too cold to want to be outside and a stair machine or treadmill can help you get in the run without the pounding on frozen pavement. A day or two on machines might just help you avoid the dreaded shin splints that so often come with long miles on hard frozen surfaces.
Celebrate the snow
Snow doesn't have to be the enemy of a winter training regime. Snow can be your friend if you can obtain the right equipment and can get to the higher elevations. Even if the mountainsides are too far to enjoy every day, a couple of trips to the high country can really lift the spirits. Strap on the snow shoes or the cross country skis once in a while to add some enjoyment and avoid the bone pounding streets for a day or two. Plus you can sample the coffee in the mountain towns and wow the other patrons with stories of 10 mile snow shoe runs that you completed before most of them were even able to get out of bed.
Do the long run
Getting in the long run is the most important thing you can do in the winter for 100 mile run training. Front Range runners are fortunate that there is no shortage of interesting locations for getting this done. Your long run can be completed the traditional way on running shoes, or in the mountains on snow shoes or cross country skis. The important thing is to get out and brave the elements for a long time. A 100 miler requires a tough mind and the only way to acquire a tough mind is to push yourself. You need to learn to keep running when you are tired, cold, hungry, sick to your stomach, discouraged, lonely and yes, afraid. Fear can definitely be a factor in the mountains at night in the dark, especially when you are cold and tired. The long runs will also teach you to discover and overcome the minor injuries such as blisters and chafing.
Where to do the long run
Some of the best places for a long run in the Front Range area include, an out and back in Waterton Canyon, a few loops in Castlewood Canyon State Park, an out and back on the Mesa Trail in Boulder, a few snowshoe loops in Meyer Ranch Park near Aspen Park, a snowshoe climb to Bergen Peak in Elk Meadows near Evergreen, a snowshoe or traditional run in White Ranch Park Near Golden or an out and back through beautiful Golden Gate State Park near Golden, a couple of four mile loops through Lovell Gulch near Woodland Park, the awesome trail system in Red Rocks Canyon near Colorado Springs and the scenic out and back ruggedness of the Chicago Lakes Trail on Mount Evans. A good trick for support during the long run is to run an out and back with a friend and leave a vehicle with supplies at the turnaround point. Try not to run the long one on pavement. The 100 milers are on trails and there is no reason to risk injury by doing the long run on hard surfaces.
Use races as training runs
The excitement of an actual event is a good way to avoid burnout and assure that the long run gets completed. If you have money for travel, running a marathon or 50 miler out of town can be a welcome break from the grind of the regular routine. The camaraderie of other runners gathering for a big event is very uplifting and good training for the actual event. You will push yourself harder in a real race and these test races are a good time to try out new dietary and ERG possibilities. The last thing you want to do on the big day is try out some new food or drink and wind up on your hands and knees beside the trail facing a DNF and a year of regret.