I'm sure anyone who plays games as a way of debriefing, relaxing or otherwise escaping the drudgery of the day-to-day grind that is the fate of so many of us will be of a similar opinion to me, in that they hold a belief that a game needs to be fun. Now, I don't want to devolve into a discussion on difficulty levels, length of games or even the casual/normal/hardcore gaming "genres" that have plagued these discussions in the past. What I want to get to is the feeling of playing a game and afterwards feeling good about the time you spent playing it.
Everyone has done it at some point, be it that game of Civ that went on just too long, grinding through to a conclusion in a game you'd stopped enjoying or finally quitting in frustration far too late after countless attempts to defeat the same segment. All of these (and many more) can lead you to that point where you ask yourself: "What was the point of all that?"
I'm more that willing to debate (at length) the merits of gaming and more importantly the validity of gaming as a hobby and also a medium (again - I don't really want to get into that here). And this is where I must say that at times I've "burnt out" on gaming. I reach a point where I just say: "That's enough." Then for several weeks I'll be in a state of malaise where I just can't play any game for more than a few minutes (even seconds sometimes) without a sense of "I really can't be bothered with this" setting in.
I'm thankful for these periods of downtime - it lets you sit back and get some perspective where you may have previously been lacking it. It gives you an excellent opportunity to catch up with other hobbies that you may have been slacking off in. And finally - when the bug finally bites you again, you have a renewed passion and can come back into gaming with a vengeance.
However these attacks of CBF syndrome are usually associated with that un-fulfilling feeling which I mentioned earlier. What makes something un-fulfilling? For me it is usually when something stops being fun and starts being a chore. It's why MMO's have never appealed and aside from very brief but intense dalliances with Diablo 2 and Titan Quest, grinding RPGs remain something which I hold no small degree of disdain for. But I can get fulfillment out of some intense grinding too - because sometimes to get that feeling you just have to overcome something. Finally beating that boss or level or even the game after so many failed attempts can give you that rush (however mild).
For many non-gamers this can be hard to quantify. The most frequent question I'm called upon to answer is: "but what do you get out of it?" The best retort to these people is usually: "what do you get out of reading a book or watching a film or completing that sudoku challenge or finally seeing that plant you've been raising flower?" Because that's what this can be. The book and films analogies are obvious - because entertainment across many mediums from reading the highest levels of academics literature to partaking in a lap-dance can be a fulfilling experience. Completing the sudoku puzzle is also obvious - you have a concrete sense of achievement in what you've done. And thus we lead into the plant, you can experience this victory across many senses, smell it, see it, touch it, in some cases taste it, you have a prize to show for your struggle.
Sadly, this is where I must give credit where credit is due and praise Microsoft for leading the charge with achievements. Even mindless grinding is rewarded with these, and having that little bar flash up at the bottom of the screen is often enough to bump up my feeling of fulfillment to a point where I'm happy that I've just spent an hour trying to get my car to flip just so in Burnout Paradise, despite all the frustration that I've felt in the meantime. If I'd quit at any time up to that point, that game would have been back on my gameshelf and gathering dust for the next few months, but with that feeling of achievement and that quantifiable object to show for that time spent it somehow all seems somehow worthwhile. Until your wife cracks the dirts with you for not helping hang up the washing.
Am I saying that having achievements makes crappy gameplay excusable? Hell no. What I'm saying is that achievements, live scoreboards, taunting e-mails (damn you Audiosurf) and things like ranks in CoD4 and Vegas all give you something to show for that time spent gaming. And even that tiniest bit of justification can make all those hours of gaming feel that little bit less like time ill-spent.