As a triathlete/runner, I am always making decisions for my training and my clients. It is January, I am in my 2nd Base Phase. Today schedule called for running hills for 5-6 miles but weather this morning was 15 degrees with wind chill of 5 degrees. Already started to feel my sinuses not happy and cold can trigger a migraine. My decision was to get on the bike for 50 minute doing 3 sets of tempo (flat and hill). Sinuses thanked me for that. Okay now when will the run happen? Tomorrow after I teach Triathlon Swim early, I will do a Fartlek/Interval run for an hour on the track at work. It will be quiet because of the snow. Thursday easy short bike and run.
Living in New England, you have to be smart and flexible with your training for January and February. When my triathletes and runners switch their workouts around, I listen why. They are being smart to know their limitations and they get it done. It is not worth to get injured or sick then you start go backwards.