Kevin Surace suggests limiting yourself to one complaint per day. Most people generate dozens of complaints internally, but restricting yourself to one forces awareness of what actually matters and protects moments of joy from constant negativity.
Chapters
I get one complaint a day, and I live by that rule. Now, here's what's interesting. Most humans, if you count them up tomorrow, all of you listening, you are going to get to 50, 80, 100 complaints a day. 100 complaints a day, internal or external. You don't voice all of them. Some of you will voice all of them. My mom probably voices all of them, but most people don't voice all of them. So the thing is, limit yourself to one a day, which is gamification of this, because if you're complaining all the time, you can't stop to find your moments of joy. So you got to stop complaining because 'Cause they're joy killers. This is what's fun. You get up in the morning, you normally go, oh, I worked out, my knees hurt. You're done for the day. You're done for the day. So all of a sudden now you start getting up, you go, nope, not gonna complain about anything. I can't use up my one complaint. I gotta save it 'cause I might need it later in the day.