Complaining is a habit that trains your mouth. Do it enough and it becomes your default setting.

Speech wears grooves the way a path does. Say the sour version enough times and it becomes the first sentence available, arriving before you have decided whether you even feel that way. This is separate from real complaint about real problems, which deserves saying out loud. The risk is the low grade version that runs all day and quietly sets the weather.

For one afternoon, count them without judging any of them. Noticing alone usually brings the number down. Then take the single complaint that is actually about something you can address, and address that one instead of narrating it.