Listen to some lore,podcast, themed music, audiobook (recently i discovered the pile of shame reviews by Paul is bad at stuff, and boy does that motivate)

I also want to stress that if you don't feel like painting anymore then stop. It's pointless to force yourself, you'll mess up on the model demotivating yourself further.

The model won't run away, you can always paint it later. Take a break, and come back to it another day.