In really cold winters it does become difficult to motivate yourself to ride your bicycle to work when you could be alternatively using a heated car.
About 25 years ago, I decided to force myself to bicycle by stopping to buy yearly car parking permit. Back when I stopped buying the permit, the yearly cost was about $900. Now it is about $1,400 per year.
On some exceptionally cold days, I just pay the daily fee ($10) when I must use a car. Savings to be used for buying bicycles or parts has proven fairly good motivation.
If your work place provides a free parking, this story is quite useless for you. 😉