My word is my bond, period
Made a commitment to a neighbor to help him move this Saturday. Rain's coming, I'm tired, got a list a mile long at home. But I said I'd be there and I'm going to be there. That's it. Your reputation is built on whether you do what you say you're going to do. My kids are watching. My wife is watching. Keeping my word costs me nothing but broken commitments cost me everything.
Throw on a rain jacket and power through it man. Your kids are learning what it means to keep your word just by seeing you do it. That's worth more than a day of rest.