Anecdote: I've made suggestions to someone on how he might optimize the time he spends writing for his various projects, and more than once he's responded that a given strategy would make it feel too much like work (I don't remember off hand if he said explicitly that this would be an instrumental problem, or if that was only implied). I'm not really sure how I feel on how I might go about applying this concept, mostly because of my extremely vague definitions of work / play, but I do find that having certain restrictions--something as simple as paper size, for example--tends to make it much easier to work on something. (I wrote a shortstory by specifying what it would need to fit in, and measuring books I'd made in the same format years earlier; I made a large number of maps for a game by using a format restricted to 32 tiles across, etc. I haven't found good ways to apply this strategy to most of what I try to do, though.).