Many things can affect our mood. Including the cold winter weather.
Unfortunately, the professionals can't afford to fall into the excuse trap. Because once you start, it's all done into the rabbit hole.
The weather is bad; I feel tired, I can do this tomorrow.
It's all excuses and you might have the best excuse in the world which worked when you are in highschool, but when you grow up, no one will give you points for your excuses.
If you want to see proof, look no further than tennis players. They need to play no matter the circumstances, because at the end of the year they will be judged not because of the good excuses, but by the rank they took during the year.