Why, music of course. I set my mp3 and rock out while cleaning all 8 bowls every three days. And I dance around like a fool which gets my guys 'n gals all riled up silly.
I know that cleaning can be a bore and at times overwhelming but change it up until you enjoy it. Switch up the order, try trading their bowl/tank location each clean (but watch afterwards to make sure they aren't uber stressed by it). The more positive energy you can put into your bowls and the cleaning process the happier you and your bettas will be for it. FYI, they really do like to dance with you. It will do you good to rock out for a bit and even if you want to sing along, they are rarely critical. (I've only had one swim into his cave while I was singing Madonna. Little snot. lol)
Caffeine helps...me at least.
So, to sum it up:::: Dance like bettas are watching, switch it up, and sing to the grumpiest fish the longest.