"Men are disturbed not by things that happen, but by their opinion of the things that happened." - Epictetus
2,000 years ago it was still true. It is not what happens, but how we think about what happens. Weather is neither good nor bad, it simply is weather. It is our opinion of the weather that gives it the meaning we choose. The economy is the economy, and it is what we think about that--our opinion about it that determines how we are choosing to feel about it and respond or react to it. To one it could be a boom time, to others a down time. It is only the interpretation that means anything.
There is more joy in my life since I have really understood this. I have no need to be upset about anything, for that would be my interpretation of an event or situation. Since, I now know that I am in 100% total control of what I choose to think about anything, I now know that I can choose to have pleasant thoughts instead of unpleasant ones. They feel better, I feel better, people around me feel better, and my life is enjoyable without the need of drugs or other diversions.
Besides changing your life for the better, it will change your business for the better. A slow day, a busy day, those are all interpretations. It is a day. Think of what you can do to give joy to another person through your personality and your business offerings. It will change you and your business for the better.