I've effectively used a variation of this: setting a daily deadline for when all work must be finished, following which I will do something (specifically planned in advance) that I enjoy. It's like being about to go on vacation.

These ideas could both be considered variations on Neil Fiore's concept of the "unschedule", and there are other authors/speakers who've promoted the idea of clearly separating work/non-work days, e.g. Eben Pagan's "Altitude" and "Wake Up Productive" programs.