Inspiration has an expiration date. Like milk, therefore, "INSPIRATION IS PERISHABLE. We all have ideas, ideas are immortal. They last forever. What doesn’t last forever is inspiration. Inspiration is like fresh fruit or milk: It has an expiration date. If you want to do something, you’ve got to do it now. You can’t put it on the shelf and wait two months to get around to it. You can’t just say you will do it later. Later you won’t be pumped up about it anymore."
ReWork - Jason Fried & David Heinemeier Hansson