I confess my testing motivation is fear - fear that if I don't know my BG, I can't correctly treat my diabetes and I risk complications. But I guess some people would suggest that they would rather not know so their fear controls them not to test.
Looking it more positively, some of my hobbies are easier/more fun if my BG is in range. For example, I have no energy to climb if my BG is too high.
So, perhaps, you could find something you enjoy which is better when your BG is in range ... or something you want to do but diabetes is holding you back.
Other than that, I would just suggest trying to make it a habit like cleaning your teeth is a habit every morning and every night.