Requiring user to click ‘Filter’ button on Reports

My app is a SPA which currently loads reports as soon as they are visited, and each time a filter is updated. Because of performance issues on the backend, I need to change this so that the data only loads after filters are chosen and a 'Generate Report' button is clicked.

I'm trying to figure out the best way to notify a user once they've changed a filter that they need to click the 'Generate Report' button again. I could initially disable it until a filter is selected, because that will make a noticeable change to the button when it's re-enabled but I'm not sure what to do after that. I was thinking some sort of animation on the button each time a filter is changed - like maybe temporarily making it brighter or temporarily dimming it. I haven't been able to find good examples of how to handle this. Any help is appreciated