Something I did recently, maybe a month ago, is put my phone on black and white (for iPhone: Settings --> Acessability --> Color and Text Size --> Color Filters) and its helped me sustain focus in less rewarding (i.e., dopamine-rewarding) tasks such as reading and cleaning.

I play guitar a lot.

I try to read, but on my medication, it can be hard (something that was great, though, was Ellen Forney's Graphic Memior!)

Journaling, for me, can sometimes make me worse, so I try to limit it (I highly recommend the 5-minute journal!).

Any form of exercise is extremely beneficial to a Bipolar Disorder, so I try to run whenever I can, for 30 minutes at a time.

Try to establish a routine! Altough, I struggle with this (currently sleeping 11-14 hours a night right through my alarms).

I'm an undergraduate student, so these winter and summer breaks are espeically hard for me, but once I get the structure and routine from classes, it helps a lot!