It seems to make common-sense from life experience that fear of imminent death and positive, unburdened, playful states of mind are both highly motivating in different ways. And to some degree, I think struggling with limited resources is often a contributing motivator that is often extinguished with over-resourced situations. This is of course partially orthogonal to individual personality, work style and other motivations. For me, getting away from most stimuli and not having a particular goal or timeframe leads to the most productive idea generation state; that is, when one lets their mind wander and play with ideas. Other people go to places like bric-à-brac stores, flip through catalogues, surf the web or seek more stimuli for inspiration.