My company is short of drivers. Has been for months, and rather than hire more, we've all been playing shuffling games between our regular runs and makeup runs to keep everything covered. 3 months ago I told them I can't work Wednesdays for the foreseeable future due to a mandatory university commitment in the morning and an absolutely necessary medical trial appointment in the afternoon. The first Tuesday before the first day I was supposed to have off they begged me to work, because “absolutely no one was available” (read: no one remembered I was taking the next day off) and I moved things around and made arrangements so I could work Wednesday, with the understanding and agreement that I absolutely could not work any further Wednesdays and would not be able to cover them under any circumstances in future.
Cut to two weeks ago, the school term ended, and as happens at the end of every school term, we had a couple of drivers finish up with the company. As noted, we've been short of drivers for a while now and 3 more leaving just made a bad situation worse. So, the company has had 2 weeks to do something about getting new drivers and training them on regular runs. When I heard more drivers were leaving, I said to myself “I'll bet myself a cheat day that they don't do anything about it and they'll call me begging me to cover the first Wednesday after school goes back when they suddenly remember they have no one to cover the Wednesday run.
Well, it's 4:30pm Tuesday and I just got the expected call begging me to cover tomorrow. No small degree of pleasure telling them “sorry, no way I can do it, for the reasons previously described and agreed to”, and also I get a night off from the gym. Double win.