Hm-m-m-m... well... I'm retired at this point. So I have time on my hands.

One way I fill it is to do very repetitive household chores. When I'm doing these things my mind tends to wander. In my case, I tend to ruminate on things.

One thing that helps is listening to music. However that's not always practical either. So another technique I use is that I recite mantras. I've memorized a few & I recite them to myself while I work. It tends to dispel my repetitive thoughts... at least while I'm chanting. Unfortunately my ruminations do typically return when I stop chanting. So chanting is not a cure. But at least it helps.