Practical implementation of gamifing:

Carma system on lesswrong create some kind of a game which encourage to write more comments

Gaming on stock exchange or looking on it could eat a lot of time. So game may be addictive and destructive to other non gamified behavior - I know it on my self.

But looking on own weight each morning is the best way to make its loosing a game - and it is know and working practice.

In fact I know see that I spent most my time on gamified activities, but some of them are not useful.