You can hope that the science in this article doesn't apply to your dog.
You can hope the coughing is just allergies.
Hope the low energy is just aging.
Hope that everything you're noticing is nothing.
Maybe they'll get better. Maybe they won't.
Imagine what this looks like in six months if something doesn't change:
The cough is still there, maybe a little worse. Maybe a lot. You've Googled it 100 times. You've asked the vet and been told it's probably allergies, probably age, probably nothing to worry about.
But you know your dog. And something tells you it isn't nothing.
The spark that used to be there when you picked up the leash is fading.
Not all at once. Just a little more each month.
And the window to do something about it gets a little smaller every day you wait.