Fair point. Passion and business don't often go hand in hand. But you will have at least a better chance of sticking with it if you care about it.

Not every idea is a good one, but at least parse through the ones you have and look for a personal angle that you can get excited about.

The other angle is not so much building on your passion, but building on your pain. If there is a pain point in something you do that is really a problem for you, then maybe you can solve it and stay energized because you are solving your own problem.