You can't use external motviation to create a passion in people. You can spark motivation by having it 'rub off' from your own passion, you can give people freedom of expression and choice, and you can use authority to keep them doing something when they are in a slump.

It can be a bit frustrating because love from small kids feels very unconditional, although they just learn that if they please you, they get food, shelter and (hopefully) positive emotions. And if you get very excited for them coding, it might motivate them to do more (since it feeds them to please you). This sounds more harmful than it is, just something to bear in mind.

Now there are various ways to appeal to intrinsic interests in kids to have them pick up something, but if it just doesn't ring with them, you can't force it.

The cool thing about computer science/engineering is, that your kids will most likely have lots of contact points in their life with CS fields. Health is getting more and more high-tech, and art is using arduinos, microcontrollers, ... for installations and various effects, depending on the direction the artist goes. So don't give up hope yet, you might be doing a project together before you know it :)