How to deal with slow days.

How do you deal when sales are slow. I have a brand that has been doing consistent sales for the past 3 years. I wouldn’t say things are going bad but I want to know how to manage slow days. When I have days where i don’t make any sales I feel like I don’t deserve to go out and do fun activities and I would rather stay at home and figure out why the day was bad and what I can do better. Do you have any tips on how I can manage my emotions on those slow days? Thank you!