Running Out of Ideas
An active and creative mind will never run out of new ideas. However, you have a responsibility to keep your creative mind active if you want the ideas to keep coming.The only thing I might add is that if you make a practice of saving your ideas, in time you won't be able to turn around because of all the saved ideas crowding in around you.
Try to use all of your ideas all the time. Don't "save" an idea for something better. There will always be new ideas, but if you start "saving" your ideas, instead of challenging yourself to come up with something else new again, you won't keep your mind active, and you will end up out of practice. You'll get yourself out of the habit of having new ideas.
So, even if a new idea doesn't suggest a complete work right away, use it anyway. Make a sketch, write a note, or write a few lines of a song. Maybe it will spark something new, or maybe it will combine with some other idea in an unexpected way.
I speak from sad experience. My filing cabinets are overflowing with half-finished work I'll get back to "some day." As I type this I'm surrounded by 30 years of notebooks, partial ms. in archives boxes, etc., etc. And don't even get me started on the electronic files.
Write. Finish what you start. Saving every idea that crosses through your mind can be a self-defeating behavior.