I would see two ways: one would be to get on your own bike. I think kids always want to be like their parents in some way.
Another one is if you have a friend with a child who balance bikes, it'll spur them on.

Be patient, and have the bike available to him/her on outings, etc. I think it'll come eventually!

My nephews all balance biked, and once they did it made walking with them much faster!