Here’s what helps me review regularly:
- I study when there are no better things to do. When I commute it’s either reading or drilling. It’s easier to resist temptation when there’s less temptation.
- I have a pact with myself that I will keep review counts low by whatever means necessary (even moving learned cards back to new), but in exchange I have to review all cards every day.
This way I have less temptation + less frustration ("I’m not going to finish these 1000 cards anyway") + more motivation ("Gotta review these 300 cards faster and have more time for reading").
It’s all about the balance of incentives. It sucks more to betray my routine, miss my usual satisfaction when I finish the reviews and pile up work for tomorrow than it is to drill an always manageable number of cards then feel good and have fun.
As for game-like elements, there’s "% learned" (overall progress), "review %" (today’s performance). Increasing both feels good because better scores == less cards to repeat tomorrow == less reviews in the coming days and in the long run == more time for reading.