When they've been making Halo games, they spent a lot of effort designing the perfect, most engaging 10-second experience. They figured that if they can make a game that's really fun to play for 10 seconds, they can repeat this 10 seconds fragment indefinitely, making the whole game very fun. It worked.
I keep that in mind when I design a UX for my app, or think about tweaking my work/hobbies to be more fun and optimized for flow.
Nail the 10 seconds that hook your brain, then just repeat.